Ascorbic acid attenuates gasoline-induced testicular toxicity, sperm quality deterioration, and testosterone imbalance in rats

The present study evaluated the protective effect of ascorbic acid (ASCB) against gasoline fumes (PET) induced testicular oxidative stress, sperm toxicity, and testosterone imbalance in Wistar rats. Twenty-four (24) male albino rats (75 ± 16 g) were randomized into three experimental groups (N = 8). The control group: received normal saline, PET group: exposed to PET 6 h daily by inhalation in an exposure chamber and PET + 200 mg ASCB/kg body weight group: exposed to PET 6 h daily by inhalation and administered ASCB per os. Treatment of ASCB and PET exposure was done thrice and five times weekly for a period of 10 weeks respectively. ASCB co-treatment prevented PET-induced increases in the oxidative stress markers (glutathione, glutathione S-transferase, superoxide dismutase, catalase, hydrogen peroxide generation, nitric oxide, and lipid peroxidation) and serum testosterone concentration (p < .05). Sperm quality was low and those with damaged heads and tails increased alongside histological injuries in the PET-exposed rats, which were also minimized with ASCB administration. ASCB protected against PET-induced oxidative stress, sperm, and testis damage in rats.

An association weight matrix identified biological pathways associated with bull fertility traits in a multi-breed population

Using seven indicator traits, we investigated the genetic basis of bull fertility and predicted gene interactions from SNP associations. We used percent normal sperm as the key phenotype for the association weight matrix-partial correlation information theory (AWM-PCIT) approach. Beyond a simple list of candidate genes, AWM-PCIT predicts significant gene interactions and associations for the selected traits. These interactions formed a network of 537 genes: 38 genes were transcription cofactors, and 41 genes were transcription factors. The network displayed two distinct clusters, one with 294 genes and another with 243 genes. The network is enriched in fertility-associated pathways: steroid biosynthesis, p53 signalling, and the pentose phosphate pathway. Enrichment analysis also highlighted gene ontology terms associated with 'regulation of neurotransmitter secretion' and 'chromatin formation'. Our network recapitulates some genes previously implicated in another network built with lower-density genotypes. Sequence-level data also highlights additional candidate genes relevant to bull fertility, such as FOXO4, FOXP3, GATA1, CYP27B1, and EBP. A trio of regulatory genes-KDM5C, LRRK2, and PME-was deemed core to the network because of their overarching connections. This trio probably influences bull fertility through their interaction with genes, both known and unknown as to their role in male fertility. Future studies may target the trio and their target genes to enrich our understanding of male fertility further.

Effect of antioxidants on semen parameters in men with oligo-astheno-teratozoospermia: a network meta-analysis

BACKGROUND

Although antioxidants are largely used in subfertile men with oligo-astheno-teratozoospermia (OAT), the choice among different molecules is challenged by the lack of comparative head-to-head studies. The network meta-analysis (NMA) can overcome limitations of pairwise meta-analyses, since it incorporates direct and indirect evidence into a single model generating an effectiveness hierarchy.

OBJECTIVE

To assess with a NMA the effects of antioxidants in improving seminal parameters in idiopathic OAT.

MATERIALS AND METHODS

PubMed, Scopus, Cinahl, and Cochrane Library databases were searched for randomized controlled trials (RCTs) comparing any antioxidant treatment to each other or placebo in men with at least one idiopathic seminal abnormality. Data were included in a random-effects NMA, where efficacy of treatments was ranked by surface under the cumulative ranking curve (SUCRA).

RESULTS

29 RCTs provided information on 2045 men (mean age: 33.5 years) with idiopathic OAT and 19 antioxidant preparations. Compared to placebo, l-carnitine, especially in combination with l-acetyl-carnitine (LAC), had the highest SUCRA for sperm concentration, progressive motility, and morphology. Folate was the only other compound effective on sperm concentration. Vitamin E+selenium or zinc had the highest SUCRA for total motility. A contribution on progressive motility was revealed for pentoxifylline and vitamin E+CoQ10.

Associations between Sperm Epigenetic Age and Semen Parameters: An Evaluation of Clinical and Non-Clinical Cohorts

The well-documented relationship between chronological age and the sperm methylome has allowed for the construction of epigenetic clocks that estimate the biological age of sperm based on DNA methylation, which we previously termed sperm epigenetic age (SEA). Our lab demonstrated that SEA is positively associated with the time taken to achieve pregnancy; however, its relationship with semen parameters is unknown. A total of 379 men from the Longitudinal Investigation of Fertility and Environment (LIFE) study, a non-clinical cohort, and 192 men seeking fertility treatment from the Sperm Environmental Epigenetics and Development Study (SEEDS) were included in the study. Semen analyses were conducted for both cohorts, and SEA was previously generated using a machine learning algorithm and DNA methylation array data. Association analyses were conducted via multivariable linear regression models adjusting for BMI and smoking status. We found that SEA was not associated with standard semen characteristics in SEEDS and LIFE cohorts. However, SEA was significantly associated with higher sperm head length and perimeter, the presence of pyriform and tapered sperm, and lower sperm elongation factor in the LIFE study (p < 0.05). Based on our results, SEA is mostly associated with defects in sperm head morphological factors that are less commonly evaluated during male infertility assessments. SEA shows promise to be an independent biomarker of sperm quality to assess male fecundity.

The Association between Abstinence Period and Semen Parameters in Humans: Results in Normal Samples and Different Sperm Pathology

BACKGROUND

The impact of sexual abstinence on sperm quality, particularly in pathological cases, is a subject of debate. We investigated the link between abstinence duration and semen quality in both normal and pathological samples.

METHODS

We analyzed semen samples from 4423 men undergoing fertility evaluation, comprising 1256 samples from healthy individuals and 3167 from those with conditions such as oligozoospermia, asthenozoospermia, teratozoospermia, or a combination of these factors, namely oligoasthenoteratozoospermia (OAT). Parameters including sperm concentration, the percentage of progressively motile spermatozoa, total motile sperm count, and the percentage of spermatozoa with normal morphology were assessed at various abstinence durations (each day, 0-2, 3-7, and >7 days).

RESULTS

Extended abstinence correlated with higher sperm concentration overall (p < 0.001), except in oligozoospermia. Longer abstinence reduced progressive motility in normal (p < 0.001) and teratozoospermic samples (p < 0.001). Shorter abstinence was linked to higher morphologically normal sperm in normal samples (p = 0.03), while longer abstinence did so in oligoasthenoteratozoospermic samples (p = 0.013).

CONCLUSION

The findings suggest that a prolonged abstinence time is linked to higher sperm concentration, while optimal sperm motility is observed after shorter abstinence periods. However, results regarding morphology remain inconclusive. Recommendations on abstinence duration should be tailored based on the specific parameter requiring the most significant improvement.

Cryopreservation-Induced Morphological Changes in Freshwater Fish Sperm: A Systematic Review

A systematic review was performed to summarize the scientific evidence and critically evaluate the effects of cryopreservation on sperm morphology in freshwater fish, and to assess the methodologies for sperm morphology classification. The search strategy was applied to four electronic databases (CAB Direct, Pub Med, Scopus, and ISI Web of Science). The main inclusion criteria involved studies on semen from freshwater fish subjected to the cryopreservation process and evaluation of sperm quality through morphology. The risk of bias was assessed with respect to randomization, allocation concealment, blinding, incomplete outcome data, and selective reporting. A total of 6 publications reporting sperm cryopreservation from 4 species with a total 74 fish individuals were included in this review. A high methodological variability among the results of the studies was observed due to the species-specific protocols and diversity of freshwater fish species studied. All included studies reported negative effects of cryopreservation on sperm quality, especially morphology, highlighting the increase in incidence of sperm abnormalities. However, only five studies statistically compared abnormalities between groups (fresh and cryopreserved sperm). Our results suggest the need to elaborate on a new morphological classification of fish spermatozoa, by considering the structure and physiology of fish sperm. This classification should be developed based on the sperm characterization and observing damage caused by different cryopreservation protocols.

Association between sperm morphology and sperm count of boar semen

The number of spermatozoa in the ejaculate is important for its quality and that of the sperm contained in it. The number of ejaculated spermatozoa is also associated with sperm dimensions. The aim of this study was to assess the morphological structure of sperm and the frequency of morphological abnormalities in sperm on the ejaculation performance of boars, measured as the total number sperm per ejaculate. The study was conducted using 648 ejaculates collected from 31 Large White boars and 30 Landrace boars. All ejaculates were analysed for basic physical characteristics and the frequency of sperm with morphological abnormalities. In addition, morphometric measurements of the sperm were made and used to calculate their shape indexes. As a result of our study it was noted that sperm from ejaculates with the most spermatozoa have shorter heads with a smaller area than sperm from ejaculates with a small or intermediate number of spermatozoa. Landrace boars produce semen of better quality, with a smaller percentage of sperm with major abnormalities, and the differences between the breeds increase with the number of spermatozoa in the ejaculate. The sperm from Landrace boars have larger heads and longer flagella than the sperm from Large White boars. The differences in sperm dimensions between breeds decrease as the total number of spermatozoa in the ejaculate increases. The number of spermatozoa in the ejaculate was shown to influence the dimensions of the sperm. The effect of the number of ejaculated sperm on ejaculate characteristics and sperm morphology depends on the breed of the male.

Performance evaluation of sperm concentration, motility, and morphological analysis for GSA-810 series of sperm quality analysis system

BACKGROUND

The performance evaluation of each computer-assisted sperm analysis (CASA) system may provide a basis for the interpretation of clinical results and further improvement of the CASA system.

METHODS

The accuracy of the GSA-810 CASA system was evaluated by detecting latex bead quality control products. The precision of sperm concentration, morphology, and percentages of progressively motile sperm (PR) were evaluated by coefficient of variation (CV). Three samples with sperm concentration of about 100 × 106 /mL were diluted to evaluate the linear range.

RESULTS

The detection values of latex beads were within the range of target values. The CVs of sperm concentration and PR were significantly and negatively correlated with sperm concentration (r = -0.561, p = 0.001) and PR value (r = -0.621, p < 0.001), respectively. The R2 values of the linear range of sperm concentration were ≥0.99. There was no significant difference in sperm motility and PR within 1-10 min at 36.5°C ± 0.5°C. The coincidence rates of sperm morphology and sperm head morphology for 36 semen samples analyzed by the GSA-810 system and manual method were 99.40% and 99.67%, respectively. The CVs of the percentage of sperm with abnormal morphology and percentage of sperm with abnormal head morphology were less than 5%.

CONCLUSION

The GSA-810 system can accurately analyze normal semen samples, but the repeatability of the results is poor for oligozoospermia and asthenozoospermia samples. The future CASA system for analyzing sperm morphology should focus on recognizing the middle and tail segments of a spermatozoon.

Sperm morphology and comparison morphometry measurements of two species of bats, Molossus molossus and Molossops temminckii (Chiroptera: Molossidae)

Sperm morphology is considered a species-specific character and has been used as a tool in the classification of numerous mammalian taxa. Neotropical bats have been poorly studied, and important aspects on sperm morphology have not been elucidated. The aim of the present study was to describe and compare the sperm morphology and morphometry of Molossus molossus and Molossops temminckii. A total of 14 adults specimens were analyzed from the Colección Mamíferos Lillo, Universidad Nacional de Tucumán: five M. molossus and nine M. temminckii. The epididymis were extracted and macerated in Farmer's solution, followed by a coloration with different stains. To carry out the description and morphometric analysis, microphotographs were taken under an optical, epifluorescence, and scanning electron microscope (SEM). A total of 50 sperm from each individual were measured for morphometric analysis. The length and width of the head, midpiece and tail were taken as variables. Sperm from M. molossus and M. temminckii were practically identical, both morphologically and morphometrically. In both species, a distal bulge was observed at the end of the intermediate piece in a percentage greater than 85%. The main characteristics shared between the species were: presence of acrosomal blebs in the upper half of the head of the spermatozoa; cephalic equatorial segment with filiform ornamentations; intermembrane space of head apex wedge-shaped; helical middle piece and annulus at the end of middle piece. In the present study, SEM allowed us to visualize structures, such as acrosomal vesicles, that were not detected with other types of microscopy. RESEARCH HIGHLIGHTS: The similarities in the sperm morphology between M. molossus and M. temminckii were observed with three types of microscopy: optical, epifluorescence and scanning electron, and supported by morphometric and statistical analyses.

Sperm ultrastructure of Pycnoderes incurvus (Hemiptera: Miridae)

The sperm morphology can provide helpful information about sexual selection, phylogeny, and the evolutionary history of a given animal group. However, there is limited or no knowledge of many taxa, especially those belonging to insects, a vast and highly diverse group. An example is the Miridae, or plant bugs, which belong to the infraorder Cimicomorpha (Heteroptera), where only three out of 17 families have published data on their sperm morphology. Here we described the Miridae sperm structure by analyzing Pycnoderes incurvus sperm under light and transmission electron microscopy. In this species, the spermatozoa were as long and slender as those of most insects. However, the anterior-most region was twisted, a characteristic first reported for Heteroptera. The acrosome was coated with electron-dense material, most likely extra-acrosomal. The centriole adjunct was a notably long, cylindrical and compact structure connecting the nucleus to the flagellar elements, with just clove-like electron-lucent points in cross-section, also features unique to Miridae so far. The flagella exhibited an axoneme of 9 + 9 + 2 microtubules and two symmetrical mitochondrial derivatives. The latter two partially embrace the axoneme, and each exhibits two paracrystalline areas and a bridge connecting it to the axoneme; these are considered Heteroptera synapomorphies that support their monophyly. RESEARCH HIGHLIGHTS: The P. incurvus sperm showed a twisted acrosome, the first reported for Heteroptera. The centriolar adjunct is a sole structure linking the nucleus and flagellum. The flagella presented the synapomorphies supporting Heteroptera monophyly.

Corrigendum: Editorial: Spermatogenesis: from stem cells to spermatozoa

[This corrects the article DOI: 10.3389/fendo.2023.1224313.].

Differences in sperm morphology between Alouatta palliata and Alouatta pigra are consistent with the intensity of sperm competition in each species

The intensity of sperm competition, in which sperm compete within the female reproductive tract to reach and fertilize her eggs, varies in species with different mating systems. Sperm competition is more intense in species where males cannot monopolize access to reproductive females and females mate with multiple males. In this scenario, a morphological change that increases the ability of sperm to reach and fertilize eggs should rapidly spread in the population, leading to sperm morphological differences between closely related species. Differences in sperm morphology have been reported among primate species with different mating systems. However, due to the inherent logistical and ethical difficulties to sample sperm from wild primates, the extent of variation in sperm morphology within species and among closely related species remains understudied. Here, we compared sperm morphological traits from two sister howler monkey species (Alouatta palliata and Alouatta pigra) that have different mating systems to investigate the effect of sperm competition on sperm morphological traits. We predicted that sperm from A. palliata, where females have more opportunities to mate with multiple males, would show differences in traits associated with increase sperm competitiveness compared to A. pigra where females mostly mate with the central male. We used linear mixed models to determine species differences in sperm morphology, controlling for individual variation. We found that midpieces and heads in A. palliata sperm were on average 26.2% and 11.0% longer, respectively, than those of A. pigra. Differences in these traits are important for sperm speed and hydrodynamic movement in other species and can affect fertilization success. This study provides empirical evidence of sperm morphological traits that evolved through sexual selection in sister primate species with different mating systems.

Changes in Sperm Morphology, Morphometry, and Motility from the Epididymis to the Vas Deferens in Rheas (Rhea americana, Linnaeus, 1758)

The objective was to characterize morphological, morphometric, and ultrastructural changes in rhea spermatozoa between the epididymis and the vas deferens. Sperm samples were collected from the reproductive tracts of seven adult individuals and evaluated for sperm characteristics using brightfield microscopy as well as ultrastructural features using scanning electron microscopy (SM). Mean sperm count tended to increase in the vas deferens (378.0 ± 135.0 × 10⁶) compared to the epididymis (201.0 ± 77.4 × 10⁶). Percentages of motile sperm grew from 37.0 ± 4.9% in the epididymis to 58.5 ± 7.7% in the vas deferens. The proportion of normal spermatozoa was 75.6 ± 1.8% and most common defects were bent tails (9.7 ± 0.9%). However, these proportions were not different between epididymis and vas deferens. SM analysis revealed further features of rhea spermatozoa. Normal rhea spermatozoa were threadlike with an acrosome (0.95 ± 0.0 µm), head (7.53 ± 0.01 µm), midpiece (2.08 ± 0.01 µm), and tail (30.7 ± 0.06 µm). Lengths of sperm acrosome, head, midpiece, and tail were longer in the vas deferens compared to the epididymis. Our findings suggest that rhea spermatozoa undergo a maturation process during the passage from the epididymis to the vas deferens.

Effect of freeze-dried quail egg white and yolk addition to semen extender on viability of rooster sperm stored for 6 h at 4°C

The effect of freeze-dried quail egg white and yolk addition to basic EK extender on morphology and motility of chicken broiler breeder semen was investigated. Fresh pooled semen was divided into eight parts: fresh, undiluted (control), diluted in 1:2 ratio (v/v) with basic EK extender, EK + 200 mg/ml of egg white, EK + 100 mg/ml of egg white, EK + 50 mg/ml of egg white, EK + 100 mg/ml of egg yolk, EK + 50 mg/ml of egg yolk, EK + 25 mg/ml of egg yolk. Semen samples were evaluated 15 min after dilution and after 6 h of storage at 4°C. In the fresh semen, the number of live normal sperm was the highest in semen diluted with EK + 200 mg of egg white and EK + 100 mg of egg yolk, while the highest sperm motility was in the neat semen. Semen storage reduced the number of normal sperm in all analysed semen samples. In the neat semen, the number of normal sperm decreased, in relation to the fresh not-stored samples, by 36.8% (from 72.3% to 35.5%), with EK extender by 9.2%, in samples enriched with egg white, from 8.4% (EK + 200 mg) to 10.0% (EK + 100 mg), and in EK with egg yolk addition, from 1.2% (EK + 50 mg) to 10.6% (EK + 100 mg). The highest percentage of motile sperm was observed in EK extender enriched with 50 mg of egg white (77.1%) and EK + 25 mg of egg yolk (65.3%).

Effects of Ureaplasma urealyticum infection on semen quality and sperm morphology

INTRODUCTION

Ureaplasma urealyticum (U. urealyticum) infection is primarily associated with damage to male fertility through its effects on male sperm parameters. However, its effects on sperm semiological variables remain unclear. Therefore, this study aimed to investigate whether U. urealyticum infection was associated with semen quality and sperm morphology.

METHODS

From 2019 to 2021, this cross-sectional study analyzed infective pathogens and semen variables in 1064 males (22-30 years old) recruited from our reproductive center and the general public. Routine semen parameters and normal sperm morphology rate were analyzed using methods outlined by the World Health Organization. The associations between semen quality, sperm morphology, and U. urealyticum infection were studied using general linear models.

RESULTS

The participants were categorized into three groups: (i) U. urealyticum infection (n=328), (ii) non-U. urealyticum infection (including males with urogenital tract infection symptoms but no U. urealyticum detected in their semen samples, n=377), and (iii) normal volunteers (males without symptoms of urogenital tract infection and no pathogens detected in semen samples, n=359). U. urealyticum in semen samples was observed to be associated with lower sperm concentrations (p<0.001) and a lower ratio of anterograde motile spermatozoa (p<0.001). Semen cultures positive for U. urealyticum were associated with lower normal sperm morphology (p<0.001) compared to semen cultures negative for U. urealyticum.

CONCLUSION

This study shows the importance of proper investigations for U. urealyticum during routine clinical examinations and diagnoses of males with infertility.

Selection on sperm size in response to promiscuity and variation in female sperm storage organs

Sperm cells are exceptionally morphologically diverse across taxa. However, morphology can be quite uniform within species, particularly for species where females copulate with many males per reproductive bout. Strong sexual selection in these promiscuous species is widely hypothesized to reduce intraspecific sperm variation. Conversely, we hypothesize that intraspecific sperm size variation may be maintained by high among-female variation in the size of sperm storage organs, assuming that paternity success improves when sperm are compatible in size with the sperm storage organ. We use individual-based simulations and an analytical model to evaluate how selection on sperm size depends on promiscuity level and variation in sperm storage organ size (hereafter, female preference variation). Simulations of high promiscuity (10 mates per female) showed stabilizing selection on sperm when female preference variation was low, and disruptive selection when female preference variation was high, consistent with the analytical model results. With low promiscuity (2-3 mates per female), selection on sperm was stabilizing for all levels of female preference variation in the simulations, contrasting with the analytical model. Promiscuity level, or mate sampling, thus has a strong impact on the selection resulting from female preferences. Furthermore, when promiscuity is low, disruptive selection on male traits will occur under much more limited circumstances (i.e. only with higher among-female variation) than many previous models suggest. Variation in female sperm storage organs likely has strong implications for intraspecific sperm variation in highly promiscuous species, but likely does not explain differences in intraspecific sperm variation for less promiscuous taxa.

Prominin-1 deletion results in spermatogenic impairment, sperm morphological defects, and infertility in mice

Purpose

Spermatogenesis is a complex process orchestrated by several essential genes. Prominin-1 (Prom1/PROM1) is a gene that is expressed in the testis but with a poorly understood role in spermatogenesis.

Methods

We used Prom1 knockout (Prom1 KO) mice to assess the role of Prom1 in spermatogenesis. To this end, we performed immunohistochemistry, immunofluorescence, western blotting, β-galactosidase staining, and apoptosis assay. Additionally, we analyzed the morphology of sperm and assessed litter sizes.

Results

We observed that PROM1 is localized to the dividing spermatocytes in seminiferous epithelial cells, sperm, and columnar epithelium in the epididymis. In the Prom1 KO testis, an aberrant increase in apoptotic cells and a decrease in proliferating seminiferous epithelial cells were observed. Cellular FLICE-like inhibitory protein (c-FLIP) and extracellular signal-regulated kinase 1/2 (ERK1/2) expression were also significantly decreased in Prom1 KO testis. In addition, a significantly increased number of epididymal spermatozoa with abnormal morphology and less motility was found in Prom1 KO mice.

Conclusions

PROM1 maintains spermatogenic cell proliferation and survival via c-FLIP expression in the testis. It is also involved in sperm motility and fertilization potential. The mechanism underlying the effect of Prom1 on sperm morphology and motility remains to be identified.

The first-line antituberculosis drugs, and their fixed-dose combination induced abnormal sperm morphology and histological lesions in the testicular cells of male mice

Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), Pyrazinamide (PZA), and/or their fixed-dose combination (FDC) are extensively prescribed in the cure of Tuberculosis (TB) globally. In spite of the beneficial effect, these drugs are capable of inducing cellular toxicity. Existing information on the genotoxic effects of the first-line anti-TB drugs is limited and contentious. Herein, we evaluated the reproductive genotoxicity of RIF, INH, EMB, PZA, and their FDC utilizing the mouse sperm morphology assay. Histological examination of the testes of exposed mice was also performed. Male Swiss albino mice (11-13 weeks old) were intraperitoneally exposed for 5 consecutive days to each of the anti-TB drugs at four different doses of 6.25, 12.5, 25, and 50 mg/kg bw of PZA; 2.5, 5.0, 10, and 20 mg/kg bw of RIF; 1.25, 2.5, 5.0 and 10 mg/kg bw of INH; 3.75, 7.5, 15 and 30 mg/kg bw of EMB; and 7, 14, 28 and 56 mg/kg bw of FDC corresponding respectively to ×0.25, ×0.5, ×1 and ×2.0 of the standard daily dose. In comparison with the negative control (normal saline), there was no significant difference in the testicular weight and organo-somatic index of exposed mice. There was an increase (p > 0.05) in the frequency of abnormal spermatozoa at most of the tested doses of each drug and a dose-dependent decrease with the FDC. Each of the anti-TB drugs except the FDC induced pathological lesions in the testes. These findings suggest that the individual first-line anti-TB drug unlike the FDC has the potential to provoke testicular anomalies in male mice.

Flagellum tapering and midpiece volume in songbird spermatozoa

In contrast to numerous studies on spermatozoa length, relatively little work focuses on the width of spermatozoa, and particularly the width of the midpiece and flagellum. In flagellated spermatozoa, the flagellum provides forward thrust while energy may be provided via mitochondria in the midpiece and/or through glycolysis along the flagellum itself. Longer flagella may be able to provide greater thrust but may also require stronger structural features and more or larger mitochondria to supply sufficient energy. Here, we use scanning electron microscopy to investigate the ultrastructure of spermatozoa from 55 passerine species in 26 taxonomic families in the Passerides infraorder. Our data confirm the qualitative observation that the flagellum tapers along its length, and we show that longer flagella are wider at the neck. This pattern is similar to mammals, and likely reflects the need for longer cells to be stronger against shearing forces. We further estimate the volume of the mitochondrial helix and show that it correlates well with midpiece length, supporting the use of midpiece length as a proxy for mitochondrial volume, at least in between-species studies where midpiece length is highly variable. These results provide important context for understanding the evolutionary correlations among different sperm cell components and dimensions.

Electroacupuncture Effectiveness for Treating Idiopathic Male Infertility

Background

Male infertility accounts for ∼50% of all infertility cases. The reasons for male infertility may vary, and one of them is related to an idiopathic factor that may impair spermatogenesis. Acupuncture is one of the most well-known and widely accepted alternative treatments and is becoming known as an effective complementary therapy for infertility.

Case

The case in this article demonstrated the effectiveness of electroacupuncture (EA) for improving male fertility by referring to the total motile sperm count (TMSC), sperm morphology and motility, DNA Fragmentation Index (DFI) of the sperm before and after EA, and pregnancy success in a couple with male infertility. Couples are given therapy with EA twice per week for up to 12 sessions and planned intercourse during the fertile period (ovulation). After planned intercourse, the wife became pregnant; an intrauterine gestational sac (GS) was seen on transvaginal ultrasound and her human chorionic gonadotropin urine test was positive.

Results

The TMSC parameter, sperm morphology and sperm motility, post-EA DFI was improved, compared to pre-EA. The couple was became pregnant after undergoing EA 12 times to treat male infertility.

Conclusions

This case illustrated that EA therapy for idiopathic male infertility has an effect toward improvement of the spermiogram test result, DFI, and success in achieving a pregnancy. However, further research is needed because there are many patients with different causes for their infertility.

The reversible effects of gossypol toxicity on male pigeons' reproductive performance

Background and Aim

Gossypol, a cotton seed derivative, is well known for its reversible antifertility in male reproduction across species. Its antifertility and reversibility effects on male reproductive function vary among species in dose-and time-dependent manners. In this study, the antifertility potential of gossypol in pigeons was evaluated for the first time to determine whether it might be used as a dietary supplement for pigeon population control.

Materials and Methods

Male pigeons were assigned into three experimental groups: The gossypol-treated group (n = 12), the sham control group (n = 6), and the negative control group (n = 6). There were two experimental periods: A gossypol-feeding period of 28 days and a gossypol-free period of 28 days. During the gossypol-feeding period, birds in the gossypol-treated group were fed 4 mg of gossypol extract per day. Birds in the sham control group were fed 0.5 mL of mixed ethanol and sunflower oil, while those in the negative control group were fed 0.5 mL of phosphate buffer saline. After the gossypol-feeding phase was completed, all remaining pigeons in all groups continued to receive their regular diet for an additional 28 days (gossypol-free phase). The body weight and semen quality of the birds in the experimental groups were compared to evaluate gossypol's antifertility effect.

Results

In the gossypol-treated group as compared to the control groups, the percentages of sperm motility and viability were significantly lower at 21 days, and the percentage of normal sperm morphology was significantly lower at 28 days during the gossypol-feeding period. After gossypol withdrawal, these antifertility effects were resumed and reached a comparable semen quality to the control groups within 14 days.

Conclusion

Gossypol supplementation (4 mg/day for 28 days) could lower male pigeons' reproductive performance in terms of sperm motility, viability, and sperm morphology. Such infertility was, however, reversible within 14 days after gossypol withdrawal without any side effects on the pigeons, suggesting its application as a safe contraceptive feeding for male pigeons.

Compensability of Enhanced Cytoplasmic Droplet Rates in Boar Semen: Insights of a Retrospective Field Study

Retained cytoplasmic droplets (CD) provide the most abundant sperm abnormality in boar and reduce fertility. It is still unclear as to whether high CD rates in semen portions are compensable. The aim was to explore the impact of CD in relation to quantitative and qualitative sperm traits on fertility performance of sows. Retrospective data analysis of 1497 inseminations was performed. Ejaculates (n = 260) were assigned to three groups with low (<10%), medium (≥10% to <15%), and high (≥15%) CD rates. Average sperm numbers were lowest in the high CD group (2.08 × 109/mL). Membrane integrity and mitochondrial activity did not differ between the groups. Breakpoint analysis indicated a shift towards lower litter sizes when the CD rate exceeded 11%. Group comparisons revealed no difference in litter size (p = 0.205), together with a slightly higher farrowing rate in the high CD group (p < 0.001), which coincided with higher resistance against temperature stress in the stored semen samples (p < 0.001) and a higher sperm motility (p < 0.001). In conclusion, an increased prevalence of CD in boar semen is compensable by high tolerance against temperature stress, whereas sperm numbers per dose are less relevant.

Chromosome 17 translocation affects sperm morphology: Two case studies and literature review

We present two cases of infertile males with teratozoospermia stemming from chromosome 17 translocation. The patients present karyotypes that have not been previously reported. Genes located on breakpoints (17p11.2, 9q31, and 11p15) were analysed to find the probable mechanism affecting sperm morphology. Our results suggest that ALKBH5, TOP3A, and LLGL1 interactions may be an underlying cause of abnormal sperm head morphology. Translocation of chromosome 17 occurred in conjunction with chromosome 9 and chromosome 11 translocation in the two cases, resulting in oligozoospermia and asthenozoospermia, respectively. These abnormal phenotypes may involve meiosis- and motility-related genes such as LDHC, DNHD1, UBQLN3, and NUP98. Translocation is thus a risk factor for sperm morphological abnormalities and motility deficiency. The interaction network of 22 genes on breakpoints suggests that they contribute to spermatogenesis as a group. In conclusion, this study highlighted the importance of investigating genes linked to sperm morphology, together with chromosome 17 translocation and reproductive risks. For patients interested in screening before a future pregnancy, we recommend preimplantation genetic diagnosis to reduce the risk of karyotypically unbalanced foetuses and birth defects.

Do studies published in two leading reproduction journals between 2011 and 2020 demonstrate that they followed WHO5 recommendations for basic semen analysis?

STUDY QUESTION

Do publications that involve the interpretation of the results of a basic semen analysis, published in Human Reproduction and Fertility & Sterility between 2011 and 2020, give sufficient evidence in their methodology to demonstrate that they followed the technical methods recommended in the fifth edition of the World Health Organization (WHO) laboratory manual, entitled WHO Laboratory Manual for the Examination and Processing of Human Semen (WHO5)?

SUMMARY ANSWER

Evidence of methodological agreement of studies with the WHO5 recommendations was low, despite 70% of papers stating that they followed WHO5 recommendations.

WHAT IS KNOWN ALREADY

A basic semen analysis is currently an integral part of infertility investigations of the male, but method standardization in laboratories remains an issue. The different editions of the WHO manual for the basic semen analysis (WHO1-6) have attempted to address this by providing increasingly rigorous methodological protocols to reduce experimental error. However, to what extent these methods are followed by studies that involve the interpretation of the results of basic semen analysis remains unknown.

STUDY DESIGN, SIZE, DURATION

A survey of the technical methods used to perform a basic semen analysis was conducted on studies published in two leading reproduction journals (Human Reproduction and Fertility & Sterility) between 2011 and 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The literature search was performed on the electronic databases PUBMED and MEDLINE Ovid between January 2021 and March 2021. The MeSH terms included in the search were 'sperm concentration' OR 'sperm motility' OR 'sperm morphology' OR 'sperm vitality' OR 'male fertility' AND 'human spermatozoa' NOT 'animals'. A total of 122 studies were available for analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 70% of the studies cited WHO5 in their methods section. Of the remaining studies, 10% cited the fourth edition of the WHO laboratory manual (WHO4), 7% cited both WHO4 and WHO5, 1% cited the third edition of the WHO laboratory manual (WHO3), and 12% did not cite the WHO at all. Overall methodological agreement with WHO5 recommendations was poor, with the main reason for this lack of agreement being that the research studies did not disclose specific details of the technical methods and equipment used.

LIMITATIONS, REASONS FOR CAUTION

In the case of studies that did not disclose any specific technical methods that they used, we did not attempt to contact these authors and so were unable to confirm the agreement between their technical methods and WHO5 recommendations.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest there is an urgent need to develop strategies to address standardization in reporting the results of a semen analysis for publication. This is particularly timely given the recent publication of WHO6 and ISO standard 23162 for the basic examination of human semen.

STUDY FUNDING/COMPETING INTEREST(S)

There was no funding for this project. C.L.R.B., as an employee of the University of Dundee, serves on the Scientific Advisory board of ExSeed Health (from October 2021, financial compensation to the University of Dundee) and is a scientific consultant for Exscientia (from September 2021, financial compensation to the University of Dundee). C.L.R.B. has previously received a fee from Cooper Surgical for lectures on scientific research methods outside the submitted work (2020) and Ferring for a lecture on male reproductive health (2021). C.L.R.B. is Editor for RBMO.

TRIAL REGISTRATION NUMBER

N/A.

Fast Noninvasive Morphometric Characterization of Free Human Sperms Using Deep Learning

The selection of high-quality sperms is critical to intracytoplasmic sperm injection, which accounts for 70–80% of in vitro fertilization (IVF) treatments. So far, sperm screening is usually performed manually by clinicians. However, the performance of manual screening is limited in its objectivity, consistency, and efficiency. To overcome these limitations, we have developed a fast and noninvasive three-stage method to characterize morphology of freely swimming human sperms in bright-field microscopy images using deep learning models. Specifically, we use an object detection model to identify sperm heads, a classification model to select in-focus images, and a segmentation model to extract geometry of sperm heads and vacuoles. The models achieve an F1-score of 0.951 in sperm head detection, a z-position estimation error within ±1.5 μm in in-focus image selection, and a Dice score of 0.948 in sperm head segmentation, respectively. Customized lightweight architectures are used for the models to achieve real-time analysis of 200 frames per second. Comprehensive morphological parameters are calculated from sperm head geometry extracted by image segmentation. Overall, our method provides a reliable and efficient tool to assist clinicians in selecting high-quality sperms for successful IVF. It also demonstrates the effectiveness of deep learning in real-time analysis of live bright-field microscopy images.

Effect of varicocelectomy on detailed sperm morphology parameters: An observational retrospective clinical cohort study

Although many studies suggest that varicocelectomy leads to improvement in semen parameters and morphology, its clinical efficacy remains controversial. The detailed morphological parameters described in the World Health Organization guidelines are important in terms of showing the effect of microsurgical subinguinal varicocelectomy on morphological changes.An observational, retrospective clinical cohort study was conducted with patients followed up from January 2018 to August 2021. This study included the data of 79 patients who met the criterion of undergoing at least 2 detailed morphological evaluations before and after surgery. All operations were performed by the same surgical team using the microsurgical subinguinal varicocelectomy technique.The mean age of the patients was 30.25 years. Of the patients, 63 underwent left-sided varicocelectomy and 16 underwent bilateral surgery. The sperm analysis revealed statistically significant increases in sperm volume (P = .006), sperm concentration (P = .003), total sperm count (P = .001), progressive sperm motility (P < .001), and normal morphology (P < .001). In the detailed morphological evaluation, except for the elongated head anomaly (P = .037), no other statistically significant changes were found in relation to sperm head, tail, and neck anomalies after surgery.This study makes an important contribution to the literature, being the first to use the subinguinal microscopic varicocelectomy technique in detailed morphological semen evaluation. We consider that detailed morphology examination in the selection and treatment of infertile patients may be useful in evaluating the efficacy of varicocelectomy.

Semen characteristics of ganders kept as genetic resources conservation program

The creation of genetic reserves of domesticated animal species and breeds almost become a necessity in the recent years, but there is a question what is the value of semen of males kept ex situ in vivo as gene conservation flocks. Presented studies assessed the response to semen collection by dorso-abdominal massage and the quantitative and qualitative semen characteristics of six goose breeds (Pomorska, Garbonosa, Kuban, Landes, Roman and Slovakia) covered by the genetic resources' protection program. Fourteen semen collection attempts were performed per male. In each breed there were ganders with low and high sensitivity to massage. The most positive reactions were stated in Pomorska ganders (67.9%), and the least in Kuban breed (52.60%). Individual male evaluation showed that only in three breeds (Pomorska, Garbonosa and Kuban) there were individuals showing 100% susceptibility to semen collection, in some breeds only 1-4 positive reactions (ending with ejaculation) were noted. Results obtained indicated breed and male effect on analyzed semen traits, with the exception of sperm motility. The highest number of live normal sperm (44.2% on average), sperm concentration (530 x10⁶ mL^-1 ), the highest Semen Quality Factor (92.9) and sperm motility (50.30%) were found in semen of Kuban ganders, while the lowest values of these traits (28.7%; 230 x10⁶ mL^-1 ; 11.4, respectively) in Slovakia ganders. The lowest sperm motility (38.3%) was observed in ganders of Roman breed, but comparing to the other breeds existing differences were not significant. Significant differences in sperm morphology between individual ganders were also observed.

The influence of Mycoplasma species on human and canine semen quality: a review

Mycoplasma species (spp.) are bacteria that are difficult to detect. Currently, the polymerase chain reaction (PCR) is considered the most effective diagnostic tool to detect these microorganisms in both human and veterinary medicine. There are 13 known species of human Mycoplasma and 15 species of canine Mycoplasma. Owing to the difficulties in identifying the individual species of Mycoplasma, there is a lack of information regarding which species are saprophytic and which are pathogenic. The prevalence of the individual species is also unknown. In addition, in both humans and dogs, the results of some studies on the impact of Mycoplasma are conflicting. The presence of Mycoplasma spp. on the epithelium of reproductive tract is often associated with infertility, although they are also detected in healthy individuals. The occurrence of Mycoplasma spp. is more common in dogs (even 89%) than in humans (1.3%-4%). This is probably because the pH of a dog's genital is more conducive to the growth of Mycoplasma spp. than that of humans. Phylogenetically, human and canine Mycoplasma are related, and majority of them belong to the same taxonomic group. Furthermore, 40% of canine Mycoplasma spp. are placed in common clusters with those of human. This suggests that species from the same cluster can play a similar role in the canine and human reproductive tracts. This review summarizes the current state of knowledge about the impact of Mycoplasma on canine and human male fertility as well as the prospects of further development in this field.

Comparison of two staining techniques on the manual and automated canine sperm morphology analysis

Detailed and direct analysis of semen, including sperm morphology, enables a diagnosis of male fertility. This study aimed to describe an economical and verified protocol for canine spermiograms and compare the effectiveness of Sperm Stain^® and Sperm Blue^® (Microptic, Spain) in veterinary practice. Sperm assessment was conducted manually, using a standard optical microscope, and via computerized semen analysis using the SCA^® CASA (Sperm Class Analyzer^® CASA System‐MICROPTIC, Spain). This study showed that Sperm Blue^® is a better solution for computerized sperm quality analysis of healthy dogs. At the same time, Sperm Stain^® turned out to be more helpful in identifying specific morphological defects of sperm. Automated canine sperm morphology analysis worked better with Sperm Blue stain, but Sperm Stain simplified manual evaluation of various organelles’ defects. Standard, manual examination is more error‐prone for an inexperienced andrology technician, but it seems to be still a gold standard technique for canine sperm assessment.

Consumption of Sugar-Sweetened or Artificially Sweetened Beverages and Semen Quality in Young Men: A Cross-Sectional Study

BACKGROUND

Existing literature suggests that frequent consumption of sugar-sweetened drinks may be associated with lower semen quality. Studies performed in mice suggest a dose-response relationship between intake of saccharin or aspartame, two artificial sweeteners, and sperm and testis function.

METHODS

A cross-sectional study based on data from The Fetal Programming of Semen Quality (FEPOS) Cohort, including 1047 young men (mean age = 19 years) was performed. Each male participant completed an online questionnaire on health, health behavior and diet, and provided a semen sample. The associations between consumption of sugar-sweetened or artificially sweetened beverages (moderate ≥ 3 days/week; infrequent < 3 days/week) and semen quality were analyzed using a multivariable, negative, binomial regression model.

RESULTS

Sugar-sweetened or artificially sweetened beverage consumption was not strongly associated with either semen volume, sperm concentration, total sperm count or total motility in young men. The proportion of morphologically normal sperm was 11% lower (0.89 (95% CI 0.76, 1.04)) for moderate (≥3 days/week) consumption of artificially sweetened beverages relative to infrequent (<3 days/week).

CONCLUSION

Consumption of sugar-sweetened or artificially sweetened beverages, at the levels present in this study had limited effect on the measured markers of semen quality in young men.

The sixth edition of the WHO manual on semen examination: ensuring quality and standardization in basic examination of human ejaculates

A basic semen investigation has established principles that are necessary for ascertaining reliable and internationally comparable results. Although these principles have been present in the WHO manual since its inception, the baseline issue across most published studies and practice in reproductive medicine (in which the male is considered) is repetitive failure to adhere to these principles, thereby leading to relevant comparable data and accuracy. To address this failure, the sixth edition of the WHO manual includes revised basic methods, and a complementary formal standard of the International Standards Organization (ISO23162:2021) for basic semen examination has been published. Perhaps the most significant change in the sixth edition is the reintroduction of the four-category distinction of sperm motility, which causes additional work for laboratories in changing reporting parameters but is clinically important. Another essential change is the widened focus from mainly a prognostic tool for medically assisted reproduction to additionally raising awareness of semen examination as a measure of male reproductive functions and general male health.

Correlation study of male semen parameters and embryo aneuploidy in preimplantation genetic testing for aneuploidy

OBJECTIVE

The purpose of this study was to evaluate the influence of abnormal semen parameters on embryo aneuploidy based on single nucleotide polymorphism microarray (SNP array).

METHODS

A total of 464 blastocysts from 103 PGT-A cycles were analyzed. The embryo quality and embryo aneuploidy rates were compared between different groups which divided by male semen parameters (sperm concentration, motility, morphology, and DFI) according the WHO criteria (2021).

RESULTS

The total blastocysts chromosome aneuploidy rate was 42.3% (191/452). In the teratozoospermia group, the good-quality embryo and blastocyst formation rate were lower than the normal group(44.4% vs 60.7%, P <0.01; 33.3% vs 43.5%, P <0.05), The good-quality embryo rate in normal DFI group was significantly higher than high-DFI group (59.0% vs 48.4%, P < 0.05). The blastocyst aneuploidy rate in low sperm concentration group, and high DFI group was no differences between with that in normal sperm concentration and DFI group (47.7% vs 37.8% and 44.7% vs 37.8%, P>0.05). The aneuploid rate of blastocyst in teratozoospermic and asthenozoospermia group was significantly higher than that of normal morphology and motility group (50.0% vs 34.0% and 46.7% vs 33.7%, P<0.05).

CONCLUSION

Our study revealed that sperm DFI were positively correlated with blastocyst aneuploidy rate, while sperm motility and sperm morphology rate were negatively correlated with blastocyst aneuploidy rate. Abnormal semen parameters may affect embryo quality and increase the aneuploidy rate of blastocyst chromosomes, suggesting that in clinical practice of assisted reproduction patients with abnormal semen parameters can be treated in advance to improve sperm quality, so as to reduce the impact on embryo quality and achieve a better pregnancy outcome.

Pre-treatment of ram semen extender with magnetic nanoparticles on freeze-thawed spermatozoa

Background

Extensive use of different nanoparticles caused significant concerns about their biological safety.

Objective

This study aimed to evaluate the effects of cryopreservation on ram semen after adding magnetic nanoparticles (MNPs) to separate X and Y chromosome‐bearing spermatozoa.

Methods

The experimental ram sperms in this research included treated spermatozoa (50 μg/ml MNPs) and non‐treated spermatozoa. DNA damage of spermatozoa was examined using an acridine orange (AO) assay. Sperm viability, membrane functionality, abnormality and malondialdehyde (MDA) level were also measured.

Results

Results indicated that the pre‐treatment of ram semen extender with MNPs did not significantly affect the semen parameters such as viability, membrane functionality, abnormality, as well as lipid peroxidation (LPO) levels and DNA integrity in comparison with the control group (p < 0.05).

Conclusions

These observations suggest that pre‐treatment of ram semen extender with MNPs after semen sexing did not have adverse effects on different semen parameters after cryopreservation.

In the current study, we evaluated the effects of cryopreservation on ram semen after adding magnetic nanoparticles (MNPs), then after thawing some semen parameters were evaluated.

Are sperm parameters able to predict the success of assisted reproductive technology? A retrospective analysis of over 22,000 assisted reproductive technology cycles

Background

An explosive increase in couples attending assisted reproductive technology has been recently observed, despite an overall success rate of about 20%–30%. Considering the assisted reproductive technology‐related economic and psycho‐social costs, the improvement of these percentages is extremely relevant. However, in the identification of predictive markers of assisted reproductive technology success, male parameters are largely underestimated so far.

Study design

Retrospective, observational study.

Objectives

To evaluate whether conventional semen parameters could predict assisted reproductive technology success.

Materials and methods

All couples attending a single third‐level fertility center from 1992 to 2020 were retrospectively enrolled, collecting all semen and assisted reproductive technology parameters of fresh cycles. Fertilization rate was the primary end‐point, representing a parameter immediately dependent on male contribution. Pregnancy and live birth rates were considered in relation to semen variables. Statistical analyses were performed using the parameters obtained according to the World Health Organization manual editions used for semen analysis.

Results

Note that, 22,013 in vitro fertilization and intracytoplasmic sperm injection cycles were considered. Overall, fertilization rate was significantly lower in patients with abnormal semen parameters compared to normozoospermic men, irrespective of the World Health Organization manual edition. In the in vitro fertilization setting, both progressive motility (p = 0.012) and motility after capacitation (p = 0.002) significantly predicted the fertilization rate (statistical accuracy = 71.1%). Sperm motilities also predicted pregnancy (p < 0.001) and live birth (p = 0.001) rates. In intracytoplasmic sperm injection cycles, sperm morphology predicted fertilization rate (p = 0.001, statistical accuracy = 90.3%). Sperm morphology significantly predicted both pregnancy (p < 0.001) and live birth (p < 0.001) rates and a cut‐off of 5.5% was identified as a threshold to predict clinical pregnancy (area under the curve = 0.811, p < 0.001).

Discussion

Interestingly, sperm motility plays a role in predicting in vitro fertilization success, while sperm morphology is the relevant parameter in intracytoplasmic sperm injection cycles. These parameters may be considered reliable tools to measure the male role on ART outcomes, potentially impacting the clinical management of infertile couples.

The effect of age and abstinence time on semen quality: a retrospective study

This study analyzed the effects of male age and abstinence time on semen quality and explored the best abstinence time for Chinese males among different age groups. Semen parameters, including sperm kinetics, morphology, and DNA fragmentation index (DFI), were reviewed from 2952 men. Samples were divided into six age groups (≤25 years, 26–30 years, 31–35 years, 36–40 years, 41–45 years, and >45 years) and were divided into six groups according to different abstinence time (2 days, 3 days, 4 days, 5 days, 6 days, and 7 days). The differences in semen quality between the groups were compared, and the effect of age and abstinence time on semen quality was analyzed. Significant differences were observed in semen volume, progressive motility (PR), and DFI among the age groups (all P < 0.05), and no significant differences were observed in sperm morphological parameters (all P > 0.05). There were significant differences in semen volume, PR, and DFI among different abstinence time groups (all P < 0.05) and no significant differences in sperm morphological parameters (all P > 0.05). Pearson analysis showed that male age and abstinence time were both significantly correlated with sperm kinetics and DFI (both P < 0.05), while no significant correlation was found with sperm morphological parameters (all P > 0.05). The box plots and histograms of men's age, abstinence time, and semen quality show that most semen quality parameters differ significantly between the 2 days and 7 days abstinence groups and other groups at different ages. Except for the sperm morphology parameters, sperm kinetic parameters and sperm DFI are linearly related to male age and abstinence time.

Effects of breed and ejaculate volume on sperm morphology and semen parameters of boars

The aim of the study was to determine the relation between the semen quality, frequency of sperm defects, sperm dimensions and shape, and the ejaculate volume of Large White and Landrace boars. A total of 648 ejaculates collected from 31 Large White and 30 Landrace boars were divided into three groups according to the criterion of the ejaculate volume. In this study Landrace boars produced ejaculates with higher volume, sperm concentration, and total numbers of spermatozoa than Large White boars. Landrace boars also showed a lower frequency of sperm with morphological abnormalities (P < 0.05). Landrace boars sperm had larger heads, which were by 0.15 μm longer, and by a larger perimeter and area (P < 0.05). Landrace boar spermatozoa also had a longer flagellum and were generally larger and by 2.07 μm longer than Large White boar sperm (P < 0.05). Significant differences were also found in the shape of sperm of the two breeds (P < 0.05). Landrace boars sperm had more elongated heads, and the ratio of head size to flagellum length was lower than in Large White boars sperm (P < 0.05). Sperm from ejaculates with low volume had a shorter flagellum and a greater head length/flagellum length ratio than sperm from medium- and high-volume ejaculates (P < 0.05).

Apical Sperm Hook Morphology Is Linked to Sperm Swimming Performance and Sperm Aggregation in Peromyscus Mice

Mammals exhibit a tremendous amount of variation in sperm morphology and despite the acknowledgement of sperm structural diversity across taxa, its functional significance remains poorly understood. Of particular interest is the sperm of rodents. While most Eutherian mammal spermatozoa are relatively simple cells with round or paddle-shaped heads, rodent sperm are often more complex and, in many species, display a striking apical hook. The function of the sperm hook remains largely unknown, but it has been hypothesized to have evolved as an adaptation to inter-male sperm competition and thus has been implicated in increased swimming efficiency or in the formation of collective sperm movements. Here we empirically test these hypotheses within a single lineage of Peromyscus rodents, in which closely related species naturally vary in their mating systems, sperm head shapes, and propensity to form sperm aggregates of varying sizes. We performed sperm morphological analyses as well as in vitro analyses of sperm aggregation and motility to examine whether the sperm hook (i) morphologically varies across these species and (ii) associates with sperm competition, aggregation, or motility. We demonstrate inter-specific variation in the sperm hook and then show that hook width negatively associates with sperm aggregation and sperm swimming speed, signifying that larger hooks may be a hindrance to sperm movement within this group of mice. Finally, we confirmed that the sperm hook hinders motility within a subset of Peromyscus leucopus mice that spontaneously produced sperm with no or highly abnormal hooks. Taken together, our findings suggest that any adaptive value of the sperm hook is likely associated with a function other than inter-male sperm competition, such as interaction with ova or cumulous cells during fertilization, or migration through the complex female reproductive tract.

Morphological Characteristics of the Sperm of the Peregrine Falcon (Falco peregrinus) during the Reproductive Season

The morphological characteristics of different sperm cells (normal, abnormal, and immature) in the peregrine falcon during the reproductive season were analysed. We also classified the main sperm defects found in semen. Semen samples were collected from mature peregrine falcons via cloacal massage and stained with Diff-Quik stain. The percentages of normal, abnormal, and immature sperm cells were determined by bright-field optical microscopy. The number of normal spermatozoa were greater at the initial stage and subsequently decreased during the middle and later stages of the reproductive season (p < 0.01). In contrast, the percentage of abnormal spermatozoa increased significantly in the middle and end stages of the reproductive season (p < 0.05), whereas the proportion of immature spermatozoa remained stable during the study. Head defects represented the greatest proportion of morphological abnormalities, followed by the defects in the tail and midpiece regions. A small percentage of multiple defects and cytoplasmic droplets were also observed in the falcon spermatozoa. The findings of this study might be important for the development of future conservation protocols for falcon sperm.

Sperm length divergence as a potential prezygotic barrier in a passerine hybrid zone

The saltmarsh sparrow Ammospiza caudacuta and Nelson's sparrow A. nelsoni differ in ecological niche, mating behavior, and plumage, but they hybridize where their breeding distributions overlap. In this advanced hybrid zone, past interbreeding and current backcrossing result in substantial genomic introgression in both directions, although few hybrids are currently produced in most locations. However, because both species are nonterritorial and have only brief male-female interactions, it is difficult to determine to what extent assortative mating explains the low frequency of hybrid offspring. Since females often copulate with multiple males, a role of sperm as a postcopulatory prezygotic barrier appears plausible. Here, we show that sperm length differs between the two species in the hybrid zone, with low among-male variation consistent with strong postcopulatory sexual selection on sperm cells. We hypothesize that divergence in sperm length may constitute a reproductive barrier between species, as sperm length co-evolves with the size of specialized female sperm storage tubules. Sperm does not appear to act as a postzygotic barrier, as sperm from hybrids was unexceptional.

Sperm morphology and DNA fragmentation after zona pellucida selection

Sperm DNA fragmentation (SDF) and sperm morphological defects can negatively affect ART outcomes. Consequently, there is a need for additional semen processing technique that accounts for sperm DNA status and morphology prior to ICSI. The objective was to evaluate the efficacy of an additional zona pellucida adhesion-based sperm selection for obtaining sperm populations with a high percentage of normal morphology and DNA integrity as compared to native semen and routine swim-up preparation. Semen samples from 78 normozoospermic men were subjected to swim up and placed in petri dishes coated with 48 acid-solubilized zonae pellucidae. Sperm DNA fragmentation and morphology were assessed in the native semen, the swim-up samples, and the zona-adhered spermatozoa from each patient. The mean sperm DNA fragmentation of the zona-selected spermatozoa (3.5 ± 0.7%) was significantly lower than the swim-up samples (15.3 ± 5.2%) (P  < 0.001) and native semen (24.9 ± 7.1%) (P  < 0.001). All of the samples had lower levels of DNA damage after additional selection by zona pellucida adhesion. Significantly higher percentage of sperm with normal morphology was observed after zona-adhesion selection (11.4 ± 3.9%) when compared to the swim-up samples (8.9 ± 4.3%) (P  < 0.001) or the native semen (5.3 ± 3.2%) (P  < 0.001). In 94% of the samples, the percentage of spermatozoa with normal morphology increased after the additional zona selection. This study demonstrates that sperm selection by additional zona-adhesion technique yields a significantly higher percentage of spermatozoa with normal morphology as well as a significantly decreased level of DNA fragmentation when compared to the native semen and the swim-up-only prepared samples.

LAY SUMMARY

High level of DNA folding known as sperm DNA fragmentation (SDF) inside each sperm and defects in the shape, size, and structure of the sperm can negatively affect assisted reproduction treatment (ART) outcomes. Consequently, there is a need for additional semen processing techniques that account for sperm quality prior to ART. Our team designed a simple technique using proteins from the coat around the egg (zona pellucida) to enhance sperm selection procedures based on natural sperm-egg interactions. Using this technique in combination with the most common techniques used in ART yields a significantly higher percentage of sperm with normal shape, size, and structure and a decreased level of DNA fragmentation. This sperm zona-selection technique would be beneficial if introduced in the ART practice to yield sperm with higher fertilization potential.

Modified strict sperm morphology threshold aids in the clinical selection of conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI)

For infertility treatment, the selection of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is decided by multiplying indicators (including fallopian tube factors, semen count, and semen motility), except for sperm morphology. In this study, we conducted a retrospective analysis, from implantation to birth, over a period of 5 years. A total of 1873 couples with primary or secondary fallopian tube factors and an increased defective sperm morphology rate (DSMR) were divided into different groups to receive IVF or ICSI cycles. By comparing the outcomes, we found that the F1 group (DSMR <96%, IVF group 1) had higher cleavage rate, biochemical pregnancy rate, clinical pregnancy rate, and live birth rate than the F3 group (DSMR >98%, IVF group 3; P < 0.05). In contrast, there was no significant difference in the ICSI subgroups. Furthermore, a comparison of the outcomes between IVF and ICSI showed that the S3 group (DSMR >98%, ICSI group 3) had higher cleavage rate (P < 0.001), biochemical pregnancy rate (P < 0.05), clinical pregnancy rate (P < 0.05) and live birth rate (P < 0.05) than the F3 group. However, the ICSI subgroup had a lower two pronuclei fertilization rate than the IVF subgroup (P < 0.05). Our data suggest that the sperm morphology should also be considered when selecting IVF or ICSI combined with other semen parameters before the first assisted reproductive technologies (ART) cycle, especially for males with severe sperm defects.

Characteristics of semen collected from gander included in the genetic resources conservation program

Conservative breeding ex situ in vivo is one of the most popular methods of creating genetic reserves. Unfortunately, keeping animals in small closed populations leads to inbreeding which reduces their reproductive capacity. The aim of the study was to characterize the sperm quality of 6 genetic groups of geese (northern and southern breeds) kept in Poland for many generations as genetic reserve flocks. Each breed was represented by 10 randomly selected 1-yr-old ganders, semen was collected 14 times, individually from each male, and the number of positive reactions (ended with ejaculation), semen volume, sperm concentration, and morphology were assessed. The obtained results showed a significant difference between breeds and individuals of the same group, both in males’ reaction and semen quantitative and qualitative traits. From the northern breeds 193 ejaculates were obtained in total (i.e., 45.9% of all attempts), from the southern breeds 242 ejaculates (57.6%). The volume of single ejaculate varied from 0.01 mL (one drop allowing only histological smear and sperm morphology evaluation) to 0.65 mL; sperm concentration varied from 23.0 × 10⁶mL⁻¹ to 2376.0 × 10⁶mL⁻¹; the amount of total live sperm was at a similar level in all breeds (89.6%–97.7%), while live normal cells ranged between 15.2% and 67.9% depending on breed and individuals. When keeping the genetic reserves ex situ in vivo, attention should be paid to the quality of semen and males that are poor in this respect should be eliminated, in order not to lead to an excessive weakening of the reproductive capacity of the flocks covered by the genetic resources protection program.

Longer Sperm Swim More Slowly in the Canary Islands Chiffchaff

Sperm swimming performance affects male fertilization success, particularly in species with high sperm competition. Understanding how sperm morphology impacts swimming performance is therefore important. Sperm swimming speed is hypothesized to increase with total sperm length, relative flagellum length (with the flagellum generating forward thrust), and relative midpiece length (as the midpiece contains the mitochondria). We tested these hypotheses and tested for divergence in sperm traits in five island populations of Canary Islands chiffchaff (Phylloscopus canariensis). We confirmed incipient mitochondrial DNA differentiation between Gran Canaria and the other islands. Sperm swimming speed correlated negatively with total sperm length, did not correlate with relative flagellum length, and correlated negatively with relative midpiece length (for Gran Canaria only). The proportion of motile cells increased with relative flagellum length on Gran Canaria only. Sperm morphology was similar across islands. We thus add to a growing number of studies on passerine birds that do not support sperm morphology-swimming speed hypotheses. We suggest that the swimming mechanics of passerine sperm are sufficiently different from mammalian sperm that predictions from mammalian hydrodynamic models should no longer be applied for this taxon. While both sperm morphology and sperm swimming speed are likely under selection in passerines, the relationship between them requires further elucidation.

Improvement of sperm morphology after surgical varicocele repair

Background

A causative relationship between varicocele and impairment of semen quality has been largely investigated in the context of male infertility, although its clinical benefit remains controversial.

Objective

To investigate the effect of varicocele correction on detailed morphologic microscopic semen parameters in a large homogeneous cohort of patients and to evaluate which factors could predict semen improvement after the surgical treatment.

Materials and methods

An observational, retrospective cohort study was carried out including all patients undergoing surgical treatment for varicocele from September 2011 to March 2020 in the same clinical centre. Enrolled males performed at least one semen analysis before and one after surgical varicocele correction. Primary outcome was the detailed morphologic microscopic sperm evaluation. Secondary outcomes were conventional semen analyses.

Results

A total of 121 males (mean age 24.6 ± 6.1 years) were enrolled. Using detailed morphologic microscopic sperm evaluation, a significant morphological improvement was recorded, with a reduction in head and tail abnormalities. Moreover, a significant increase in sperm concentration (p = 0.015) and percentage of progressive and total motility (p = 0.022 and p = 0.039) were observed after surgery. The multivariate logistic analysis identified the ultrasonography varicocele degree before surgery as a main predictor of the sperm concentration improvement (p = 0.016), with the highest improvement for varicocele of I and II degree.

Discussion

For the first time, the detailed morphologic microscopic sperm evaluation highlights a relevant reduction in sperm abnormalities after varicocele surgery, showing its potential application in clinical practice.

New Sperm Morphology Analysis in Equids: Trumorph® Vs Eosin-Nigrosin Stain

The evaluation of the male fertility potential is based on the analysis of the basic spermatic characteristics of concentration, motility and morphology. Thus, the study of sperm morphology is a fundamental element in the seminal analysis, but its real meaning has been biased by the techniques used for its evaluation. These techniques involve dehydration phases and subsequent staining, which involves the production of artifacts. The aim of the study is to compare two methods for equid semen morphology evaluation, Trumorph^® using living sperm vs. eosin-nigrosine stain. A total of 49 ejaculates from stallions and donkeys were used. After semen collection and dilution, an aliquot was placed on the slide and introduced in the Trumorph^® device. Then observation was made with a 40x objective and negative phase-contrast microscope. Another aliquot was stained using eosin-nigrosine stain and viewed using 100× magnification. Well-formed sperm were observed, and different abnormalities were identified using Trumorph^®. The use of eosin-nigrosin staining method and Trumorph^® led to the same results and both techniques can be used for stallion and donkey sperm morphological analysis. However, considering the fact that Trumorph^® uses living sperm helps prevent sperm cell alteration during sample preparation. Therefore, Trumorph^® can be a good alternative to the conventional staining method, which provides a quick test on live sperm.

Weapons Evolve Faster Than Sperm in Bovids and Cervids

In polyandrous species, males face reproductive competition both before and after mating. Sexual selection thus shapes the evolution of both pre- and postcopulatory traits, creating competing demands on resource allocation to different reproductive episodes. Traits subject to strong selection exhibit accelerated rates of phenotypic divergence, and examining evolutionary rates may inform us about the relative importance and potential fitness consequences of investing in traits under either pre- or postcopulatory sexual selection. Here, we used a comparative approach to assess evolutionary rates of key competitive traits in two artiodactyl families, bovids (family Bovidae) and cervids (family Cervidae), where male–male competition can occur before and after mating. We quantified and compared evolutionary rates of male weaponry (horns and antlers), body size/mass, testes mass, and sperm morphometrics. We found that weapons evolve faster than sperm dimensions. In contrast, testes and body mass evolve at similar rates. These results suggest strong, but differential, selection on both pre- and postcopulatory traits in bovids and cervids. Furthermore, we documented distinct evolutionary rates among different sperm components, with sperm head and midpiece evolving faster than the flagellum. Finally, we demonstrate that, despite considerable differences in weapon development between bovids and cervids, the overall evolutionary patterns between these families were broadly consistent.

Morphometric and structural analysis of Florida manatee spermatozoa

Sperm characteristics, such as sperm morphology and sperm morphometry are important in assessing sperm quality. This is especially important for the management and conservation of endangered and exotic species, like the Florida manatee, where information of this nature is extremely limited. In this study, we fill this knowledge gap to better understand the reproductive physiology of Florida manatees by conducting the first extensive analysis of sperm morphometry and ultrastructure. Sperm were retrieved from the vas deferens of nine recently deceased Florida manatees. Computer‐aided sperm morphology analysis (CASMA) was used for morphometric analysis and laser‐scanning confocal microscopy and electron microscopy were used for structural and ultrastructural characterization. Our findings reveal new morphometric and structural data for the Florida manatee spermatozoon. Twelve morphometric features of Florida manatee sperm were quantified with some approximately 1.5–2 times larger than those previously reported. Ultrastructurally, the Florida manatee spermatozoon followed a mammalian structural pattern with an ovate‐shaped head, midpiece containing 84–90 mitochondria, and a flagellum. However, unique ultrastructural features were identified. Distinct, rectangular‐like enlargement of four outer dense fibers surrounding the axoneme was evident, which may provide additional tensile strength to counteract the forces on sperm transiting the female reproductive tract. Likewise, strong localization of F‐actin fibers within the midpiece may function to maintain sperm integrity within the female reproductive tract. These findings highlight the potential effects of sexual selective pressures on sperm size and structure in the Florida manatee and provide avenues for research on the occurrence of sperm competition in this species.

Assessing the clinical value of the Kruger strict morphology criteria over the World Health Organization fourth edition criteria

Objective

To assess if the newer Kruger strict morphology (WHO5; normal ≥4%) adds any clinical value beyond the criteria of the World Health Organization fourth edition (WHO4; normal ≥14%).

Design

Retrospective study.

Setting

Tertiary hospital.

Patients

Men without known azoospermia who had semen analysis (SA) collected over a 10-year period of time.

Interventions

Morphology classification under Kruger WHO5 strict criteria and WHO4 criteria.

Main Outcome Measures

Correlation between the WHO5 and WHO4 morphological classifications.

Results

A total of 4,510 SAs were identified during the study period. Of these, both Kruger WHO5 and WHO4 morphologies were included in 932 SAs (20.7%) from a total of 691 men. The median age of the men was 37 years (interquartile range, 32.0-43.8 years). The mean (±SD) semen volume, sperm concentration, and motility were 2.6 ± 1.4 mL, 50.0 ± 35.6 × 10⁶/mL, and 53.1% ± 18.6%, respectively. The correlation between the WHO4 and WHO5 morphology assessments was high (Spearman correlation coefficient = 0.94). Only 545 (58.5%) of 932 SAs had abnormal Kruger WHO5 morphology, of which 543 (99.6%) of 545 also had abnormal morphology by the WHO4 criteria.

Conclusions

The Kruger WHO5 and WHO4 morphologic criteria correlate closely. Only two men (0.4%) with an abnormal Kruger morphology had normal WHO4 morphology. Given the limited predictive value of sperm morphology, the additional cost and effort of Kruger criteria may not be warranted in lieu of, or in addition to, the WHO4 classification.

Impact of chronic vitamin A excess on sperm morphogenesis in mice

BACKGROUND

The increasing availability of fortified foods and supplements has caused an overconsumption of vitamin A (VA), above the recommended level. To date, the effects of chronic VA excess (VAE) on spermatogenesis remain unclear.

OBJECTIVE

This study aims to investigate the long-term excessive intake of VA effects on spermatogenesis in mice.

MATERIALS AND METHODS

Dams were initially fed a control diet (4 IU/g) or a VAE diet (250 IU/g), 4 weeks prior to mating and during pregnancy. Dams and their male pups continued this diet regimen until the offspring reached 12 weeks of age. At 12 weeks of age, epididymis caudal spermatozoa and testes were collected. For histological analysis, sections were stained with periodic acid-Schiff-hematoxylin, and quantitative PCR was used to detect changes in gene expression in the testes of the VAE mice. Sperm motility and morphology were evaluated to detect the endpoint of VAE toxicity.

RESULTS

Body weights were not significantly different between the control and VAE groups. Testicular cross-sections from the control and VAE mice contained a normal array of germ cells, and the daily sperm production was similar between the two groups. However, the percentage of seminiferous tubules in stages VII and VIII was significantly lower in the VAE mice than in the control. In addition, significant changes in the expression of genes involved in retinoid metabolism, spermatogenesis, and spermiogenesis were detected in the testes of the VAE mice. Consistently, sperm motility and head morphology were significantly impaired in the VAE mice.

DISCUSSION AND CONCLUSION

Our findings suggest that long-term dietary intake of VAE was able to influence both pre- and post-meiotic spermatogenesis. As a result of testicular toxicity, we demonstrated, to the best of our knowledge, for the first time that long-term VAE caused sperm-head abnormalities.