Changes in the morphology of spermatozoa during their passage through the genital tract in dairy bulls with normal and impaired spermat ogenesis

Immunofluorescence Reveals Ubiquitination of Retained Distal Cytoplasmic Droplets on Ejaculated Porcine Spermatozoa

The purpose of the present study was twofold: 1) to determine if antibodies raised against ubiquitin would recognize antigens associated with the porcine cytoplasmic droplet (CD), and 2) to determine if the same antibody would identify ubiquitinated substrates on the surface of morphologically abnormal boar spermatozoa. Permeabilization with the detergent Triton X-100 (0.05%) showed virtually all CDs to be ubiquitin positive. Distal droplets (DDs) retained in situ on boar spermatozoa were readily labeled following Triton permeabilization, whereas DDs present on nonpermeabilized cells were not. Negative control preparations lacked the ubiquitin staining on the DD. The use of microtubes for fixation and incubation provided clearer images as well as better sperm cell distribution and density than an initial slide-mounted technique. Immunoblotting indicated that larger amounts of ubiquitinated proteins were present in extracts from sperm cells from an ejaculate with an abnormally high percentage of retained DDs (52% DDs) compared to a morphologically normal sample (6% DDs). The primary antibody recognized both mono-ubiquitin of bovine origin (8.5 kd) and human ubiquitin conjugate (35 kd), as demonstrated by Western blot. Preabsorption of the anti-ubiquitin antibody with purified bovine ubiquitin was successful in preventing diaminobenzidine staining of sperm extract from the high DD ejaculate. The presence of antigens recognized by anti-ubiquitin antibodies in the boar sperm CD, coupled with the possibility that superfluous ubiquitin species are detrimental to embryonic development by targeting critical paternally contributed zygotic organelles, raises concerns that retained DDs may be more detrimental to fertility than previously suspected.

Effect of FMD vaccination on semen quality parameters in Karan Fries and Murrah buffalo bulls

Effect of Foot and Mouth disease (FMD) vaccination was studied on semen quality parameters of 19 Karan Fries (KF) and eight Murrah (MU) breeding bulls during the period 2002 to 2004 at Artificial Breeding Complex, NDRI, Karnal. A total of non-vaccinated 155 KF and 72 MU bulls' ejaculates were taken as control, while 169 KF and 51 MU bulls' ejaculates, collected after vaccination, were used to study the effect of vaccination stress. The results showed that FMD vaccination had no significant (P > 0.05) effect on ejaculate volume and total volume per day of semen in both KF and MU bulls. Volume of semen increased slightly during post-vaccination period in both the breeds. After FMD vaccination, there was significant (P < 0.01) decrease in mass activity (2.27 +/- 0.06 vs. 1.67 +/- 0.07 and 2.49 +/- 0.09. vs. 1.75 +/- 0.10, for KF and MU, respectively), initial motility (56.89 +/- 0.03% vs. 44.62 +/- 0.02% and 62.26 +/- 0.04% vs. 47.08 +/- 0.05%, for KF and MU, respectively), sperm concentration (754.19 +/- 23.96 vs. 554.14 +/- 22.95 x 10(6)/ml and 848.61 +/- 33.65 vs. 571.57 +/- 39.99 x 10(6)/ml, for KF and MU, respectively), and total sperm output per ejaculate (3,685.94 +/- 158.40 vs. 2,781.54 +/- 151.70 x 10(6) and 2,218.75 +/- 133.14 vs. 1,582.84 +/- 158.20 x 10(6), for KF and MU, respectively). Application of FMD vaccine had significantly (P < 0.05) adverse effect on most of the seminal attributes during post-vaccination in KF and MU buffalo bulls. So, the spermiograms affected following vaccination suggest that in bovines, the semen collection and preservation should be suspended till normal fertility of sperm is restored to avoid the failure of conception from artificial insemination using such semen.

Regulated upon activation normal T-cell expressed and secreted originating from the epididymis differentially associates with viable and defective spermatozoa

OBJECTIVE

To investigate the expression and cellular distribution of regulated upon activation normal T-cell expressed and secreted (RANTES) in the male reproductive system.

DESIGN

Basic research.

SETTING

University academic medical center.

PATIENT(S)

Three adult male organ donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, immunohistochemical staining, and immunofluorescence staining were used to examine the distribution of RANTES in human and mouse epididymis. Western blot was used to quantitate the levels of RANTES expression in mouse epididymis on postnatal days. Immunofluorescence staining was applied to detect RANTES association with spermatozoa from mouse epididymis.

RESULT(S)

The location of RANTES was restricted to ciliated cells of the efferent duct and apical, narrow, and basal cells of the epididymal ducts, in both humans and mouse. RANTES-positive basal cells were only identified in the epididymal ducts in humans. The signals of RANTES were first detected on day 28 and increased during mouse sexual maturation. We also observed that RANTES was bound on both normal and defective epididymal sperm, but in different patterns.

CONCLUSION(S)

RANTES is constitutively expressed in the epididymis and secreted into the lumen of epididymis throughout sexual maturity, and differentially associates with viable and defective spermatozoa.

Mechanism of extracellular ubiquitination in the mammalian epididymis

Posttranslational modification by ubiquitination marks defective or outlived intracellular proteins for proteolytic degradation by the 26S proteasome. The ATP-dependent, covalent ligation and formation of polyubiquitin chains on substrate proteins requires the presence and activity of a set of ubiquitin activating and conjugating enzymes. While protein ubiquitination typically occurs in the cell cytosol or nucleus, defective mammalian spermatozoa become ubiquitinated on their surface during post-testicular sperm maturation in the epididymis, suggesting an active molecular mechanism for sperm quality control. Consequently, we hypothesized that the bioactive constituents of ubiquitin-proteasome pathway were secreted in the mammalian epididymal fluid (EF) and capable of ubiquitinating extrinsic substrates. Western blotting indeed detected the presence of the ubiquitin-activating enzyme E1 and presumed E1-ubiquitin thiol-ester intermediates, ubiquitin-carrier enzyme E2 and presumed E2-ubiquitin thiol-ester intermediates and the ubiquitin C-terminal hydrolase PGP 9.5/UCHL1 in the isolated bovine EF. Thiol-ester assays utilizing recombinant ubiquitin-activating and ubiquitin-conjugating enzymes, biotinylated substrates, and isolated bovine EF confirmed the activity of the ubiquitin activating and conjugating enzymes within EF. Ubiquitinated proteins were found to be enriched in the defective bull sperm fraction and appropriate proteasomal deubiquitinating and proteolytic activities were measured in the isolated EF by specific fluorescent substrates. The apocrine secretion of cytosolic proteins was visualized in transgenic mice and rats expressing the enhanced green fluorescent protein (eGFP) under the direction of ubiquitin-C promoter. Accumulation of eGFP, ubiquitin and proteasomes was detected in the apical blebs, the apocrine secretion sites of the caput epididymal epithelia of both the rat and mouse epididymal epithelium, although region-specific differences exist. Secretion of eGFP and proteasomes continued during the prolonged culture of the isolated rat epididymal epithelial cells in vitro. This study provides evidence that the activity of the ubiquitin system is not limited to the intracellular environment, contributing to a greater understanding of the sperm maturation process during epididymal passage.

Sperm Morphology in the Domestic Cat, and its Relation with Fertility: A Retrospective Study

Knowledge about normal ranges in semen quality and the association between sperm morphology and fertility in felids is limited. The aims of this retrospective study were to (1) define a normal spermiogram in cats; (2) evaluate possible effects of season, age and breed on sperm morphology; and (3) evaluate the relationship between sperm morphology and fertility. Semen samples collected by electroejaculation from 52 cats were evaluated for sperm morphology. The cats constituted two groups: a general population of cats (n = 48) and cats examined because of poor breeding records (n = 4). The general population was divided into household (n = 20), pedigree (n = 19) and colony cats (n = 9) and into three age classes, <12 months, 12-59 months and >or=60 months. The median percentage of normal spermatozoa in the general population was 44.0% (range 1.0-91.0%). Criteria were tentatively set for what was considered a normal spermiogram. The mean percentage of normal spermatozoa was higher during February to July than during August to January (p < 0.05). Pedigree cats had a lower mean percentage of normal spermatozoa than did household cats (p < 0.05). Age had no effect on the percentage of normal spermatozoa but was positively correlated with the percentage of proximal droplets. Of the cats with <40% normal spermatozoa (n = 19), all those with known breeding records (n = 11) had produced litters. The four cats examined because of poor breeding results had higher percentages of different sperm abnormalities than tentatively stipulated for the normal spermiogram. In two of these cats both sperm morphology and fertility changed over time.

Sperm maturation in the domestic cat

The epididymis is essential for sperm development and maturation, and, subsequently, the ability of spermatozoa to penetrate and fertilize the female gamete. Functional differences in segments of the long tubule are reflected by histological differences among epididymal regions. The feline epididymis can be divided into six different regions according to their histological differences. A marked increase in sperm concentration occurs between regions 2 and 3, indicating resorption of fluid in region 2, a concept supported by the histological characteristics of the epithelium. At the transition between regions 4 and 5, located between the caput and corpus epididymides, histological characteristics change from being that of a maturation function to being typical of a storage function. Migration of the cytoplasmic droplet and induction of motility occur in this same region. Proteins are secreted from epithelial cells in the feline epididymis by merocrine and apocrine secretion, although the functions of different feline epididymal proteins have not been determined. Hypotaurine, taurine and, probably, alkaline phosphatase are produced by the feline epididymis. During epididymal transit the percentage of immature, unviable and morphologically abnormal spermatozoa decreases, indicating the existence of a mechanism that removes abnormal spermatozoa. In contrast, the percentage of spermatozoa with abnormal tails increases slightly during epididymal transit. Most of the distal droplets present on spermatozoa in the cauda epididymis are lost at or after ejaculation. Additional knowledge of the feline epididymis should be beneficial for developing sperm preservation protocols and advance the prospects for effective male contraceptive methods.

Evaluation of fertility and infertility in natural service bulls

The potential fertility of bulls can be evaluated in the field by assessment of mating ability and physical examination. Both methods are useful for screening out low fertility bulls, although neither allows precise determination of the pregnancy rates that bulls actually achieve. Observations of coitus, libido testing and service capacity testing are the main methods of assessing mating ability in the field and, although not reliable for virgin bulls, are widely used for older bulls. Of the traits that are assessed during physical examination, those most closely correlated with fertility are scrotal circumference and the semen quality parameters of motility and morphology. Whilst these methods allow reasonable accuracy in determining the fertility potential of an individual bull, they do not take into account other managemental constraint to bulls' fertility. Although these are reasonable well understood for beef herds, the managemental factors that affect the performance of natural service sires in dairy herds are poorly understood.

Improvement in spermatogenic function after subcutaneous implantation of a capsule containing an aromatase inhibitor in four oligozoospermic dogs and one azoospermic dog with high plasma estradiol-17beta concentrations

A capsule containing an aromatase inhibitor (4-androsten-4-ol-3,17-dione) was subcutaneously implanted in four oligozoospermic beagle dogs and one azoospermic beagle dog with high plasma estradiol-17beta (E2) concentrations (15-19 pg/ml) and low plasma testosterone (T) concentrations (0.6-0.8 ng/ml) for 8 weeks and the effect of the aromatase inhibitor on spermatogenic dysfunction was assessed. Plasma E2 and T concentrations and semen quality were examined at 1 week intervals from 3 weeks before to 12 weeks after the start of treatment. Testicular biopsies were done twice (capsule implantation and removal). Plasma E2 concentrations of all dogs decreased (9-14 pg/ml) and plasma T concentrations increased (2.0-2.6 ng/ml) from 3 weeks after capsule implantation to capsule removal. The mean number of spermatozoa ejaculated by all four oligozoospermic dogs between 4 and 9 weeks after implantation was higher (127 x 10(6) to 205 x 10(6)) than before implantation (20 x 10(6) to 38 x 10(6)) (P < 0.05 and 0.01). Very low numbers (2 x 10(4) to 4 x 10(4)) of immotile spermatozoa were observed between 7 and 8 weeks after implantation in the semen collected from the dog with azoospermia. Before implantation, a few spermatozoa were seen in only one-fifth of the seminiferous tubules in this dog; 8 weeks after implantation, the mean diameter and mean number of round spermatids in the seminiferous tubules in all five dogs were higher than before implantation (P < 0.05). Implantation of the capsule containing the aromatase inhibitor in infertile dogs with abnormally high plasma E2 concentrations improved their spermatogenic function, concurrent with decreased plasma E2 and increased plasma T.

Differential ubiquitination of stallion sperm proteins: possible implications for infertility and reproductive seasonality

Antibodies against ubiquitin, a universal proteolytic marker, show increased cross-reactivity with defective spermatozoa in men and bulls. We investigated sperm ubiquitination in the stallion, a seasonally polyestrous mammal. Immunofluorescence and immunoelectron microscopy demonstrated that anti-ubiquitin antibodies bind to the surface of both membrane-intact and aldehyde-fixed spermatozoa. Cross-reactivity to the ubiquitin-conjugating enzyme E2 was also detected in sperm. Immunohistochemistry showed that ubiquitinated spermatozoa were first detected in the caput epididymis, coincident with a strong accumulation of ubiquitin and ubiquitin C-terminal hydrolase, protein gene product 9.5, in the apical stereocilia of the epididymal epithelium. Testicular spermatozoa did not display significant ubiquitin cross-reactivity. Similarly, lesser accumulation of ubiquitin cross-reactive substrates was identified in the accessory sex glands. Semen samples were collected from three fertile stallions and one subfertile stallion between December and February and probed for ubiquitin by flow cytometry and immunoblotting. Flow cytometric analysis showed that sperm from the subfertile stallion had higher ubiquitin levels than sperm from the other three stallions. In addition, immunoblot analysis of sperm proteins from the subfertile stallion showed two unique ubiquitin cross-reactive bands that were not present in sperm extracts from the three fertile stallions. To screen for a possible role for ubiquitin in seasonal changes in sperm production, semen samples from two fertile stallions were collected in March, June, September, and December and subjected to a flow cytometric ubiquitin assay. The lowest levels of ubiquitin-labeled sperm were found in March, approximately coincident with the onset of the natural horse breeding season. A progressive increase in sperm ubiquitin levels was found during summer and fall, with a peak in December. These data suggest that stallion sperm are differentially ubiquitinated during epididymal maturation and that this ubiquitination may reflect changes in sperm numbers and semen quality. The association between changes in sperm ubiquitination and seasonal changes in sperm production will be subjected to further studies in a larger cohort of animals.

Ubiquitin-dependent sperm quality control mechanism recognizes spermatozoa with DNA defects as revealed by dual ubiquitin-TUNEL assay

Defective mammalian spermatozoa become ubiquitinated during epididymal passage, a mechanism that may mark the abnormal spermatozoa for proteolytic destruction (Sutovsky et al., 2001a: J Cell Sci 114:1665-1675). It is not known how such spermatozoa are recognized by the epididymal ubiquitination pathway and whether there is a selection against certain types of sperm defects. We examined the relationship between sperm ubiqutination, lifelong sperm morphology and sperm DNA defects using a single chanel, ubiquitin-activated flow cytometric assay, and a dual, ubiquitin-TUNEL assay. Semen samples from nine service sires of good-to-average fertility were screened. A positive correlation was found between sperm ubiquitination and the average frequency of morphological semen abnormalities from field evaluations performed throughout the reproductive life of individual sires. Sample correlation coefficients were r=0.65 for primary (head and tail) and r=0.60 for total semen abnormalities in the single channel assay. In a dual assay, we found a high, positive correlation (r=0.93) between the ubiquitin-positive sperm and the TUNEL positive sperm. Substantial correlations (r=0.47-0.64) were observed when the measurements from these two respective assays were compared for individual sires. While anti-ubiquitin antibodies recognized most of the TUNEL-positive sperm cells, the TUNEL-positive spermatozoa represented only a subset (approximately 20-40%) of all ubiquitin-positive cells. It appears that the ubiquitin-dependent sperm quality control, residing in the epididymal epithelium, has the ability to detect spermatozoa with apoptotic or necrotic DNA, while spermatozoa with defects other than DNA fragmentation are also recognized and ubiquitinated.

A putative, ubiquitin-dependent mechanism for the recognition and elimination of defective spermatozoa in the mammalian epididymis

The normal structure and function of sperm are prerequisites for successful fertilization and embryonic development, but little is known about how defective sperm are eliminated during mammalian spermatogenesis. Here, we describe a ubiquitin-dependent, sperm quality control mechanism that resides in the mammalian epididymis, the site of sperm maturation and storage. We used immunofluorescence, electron microscopy, western blotting and pulse-chase experiments to show that ubiquitin is secreted by the epididymal epithelium and binds to the surface of defective sperm. Most of the ubiquitinated sperm are subsequently phagocytosed by the epididymal epithelial cells. A portion of defective sperm escapes phagocytosis and can be found in the ejaculate. Cultured epididymal cells maintain their ability to produce ubiquitin and phagocytose the defective sperm, as well as the ubiquitin-coated microspheres, in vitro. The surprising phenomenon of cell-surface ubiquitination in defective sperm provides a possible mechanism for sperm quality control in mammals and a new marker of semen abnormalities in men and animals.

Assessment of sperm morphology in zebu bulls, under field conditions in the tropics

Sperm morphology was studied in 302 extensively managed Zebu bulls (aged 1.5-9 years), classified as sound (n=166) or unsound (n=136) for breeding, under field conditions in the dry tropics of Costa Rica. Single semen samples were collected by electro-ejaculation and fixed in formol-saline solution immediately after collection. Sperm morphology was determined in the field on wet smears using a microscope equipped with phase-contrast optics, and further determined in the laboratory on air-dried smears stained with carbol-fuchsin. The frequencies of sperm abnormalities (such as abnormal acrosome, head, neck, mid-piece, tail, and presence of cytoplasmic droplets) were recorded as a percentage of the total number of counted spermatozoa (400 cells). Zebu bulls considered unsound for breeding showed a higher mean prevalence (p < 0.05) of knobbed acrosomes (4.0 versus 0.9%), head defects [specifically, nuclear invaginations and heads with abnormal shapes and sizes (27.6 versus 4.0%)], abnormal tails (11.2 versus 4.7%), and proximal droplets (8.4 versus 1.6%), compared with bulls considered sound for breeding. In these latter bulls, the abnormality most commonly seen was the presence of single bent tails with an entrapped cytoplasmic droplet (3.0 +/- 3.7%). Young Zebu bulls (i.e. bulls under 2 years of age) showed a higher percentage of missing acrosomes, and proximal cytoplasmic droplets, than older sires (12.1 versus 2.4%, and 23.9 versus 3.6%, respectively; p < 0.05), interpreted as an indication of low ejaculation frequency and sexual immaturity, respectively. Bulls with a long scrotum and soft testicular consistency (TC) at palpation showed higher percentages of abnormal sperm heads in the ejaculate than bulls with a normal scrotal length (SL) and a normal TC (32.7 versus 12.8% and 30.7 versus 10.3%, respectively; p < 0.05). In addition, Zebu bulls with a scrotal circumference (SC) < or = 30 cm showed a higher prevalence of proximal cytoplasmic droplets than bulls whose SC was > 30 cm (9.8 versus 2.6%, p < 0.05). A higher mean percentage of abnormally sized and shaped heads, especially undeveloped and narrow at the base, was more frequently found in stained smears than in unstained samples (26.0 versus 9.9%, p < 0.05), which clearly underlines the importance of using both stained and wet smears when assessing sperm head morphology. However, for a quick assessment of sperm morphology under field, tropical conditions, phase-contrast microscopy provides useful information for the spermiogramme evaluation.

Characterization of gossypol-induced sperm abnormalities in bulls

To characterize sperm abnormalities induced by gossypol in cattle, young Brahman bulls (n=8) received either cottonseed meal delivering 8.2 g free gossypol/bull/d (treatment, n=4) or isonitrogenous soybean meal (control, n=4) for 11 wk. At slaughter, semen was collected from the following extragonadal sites: mediastinum/rete testis (Site 1), caput (Site 2), corpus (Site 3) and cauda epididymis (Site 4), and ductus deferens (Site 5). At least 200 fixed spermatozoa per site were examined via differential-interference-phase contrast (DIC) microscopy, with electron microscopy (EM) being employed with select samples. Sperm midpiece abnormalities were categorized as aplastic, fragile or asymmetric, with detached sperm heads being tabulated separately. Of these, aplastic defects were considered most likely to occur during spermatogenesis. Bull sperm midpiece lesions induced by gossypol were ultrastructurally similar to those observed in other, nonruminant, species. Combined midpiece abnormalities generally increased with extragonadal passage (EGP) in the treated bulls, as did fragile and asymmetric but not aplastic midpieces, or detached sperm heads. This pattern of EGP changes in bull sperm morphology following gossypol spermatoxicity suggests that structural weakness induced during spermatogenesis leads to secondary spermatozoal changes during EGP, possibly due to the imposition of motility stressors upon prior weakened structures.

Morphology of spermatozoa in the cauda epididymidis before and after electroejaculation and a comparison with ejaculated spermatozoa in the domestic cat

When 2 ejaculates are collected by electroejaculation from the domestic cat within a period of 10 min the first ejaculate has a higher proportion of abnormal spermatozoa than the second. The reason for this difference is not known for the domestic cat, but in other species long-term epididymal storage results in a higher proportion of abnormal spermatozoa. The aims of this study were to determine the proportions of abnormal spermatozoa in the cauda epididymidis and to ascertain if electroejaculation affects this proportion. Therefore the proportions of spermatozoa in the cauda epididymidis with different morphological abnormalities were compared before and after ejaculation. In addition, the proportion of morphologically abnormal spermatozoa in the epididymis was compared with that in the ejaculate. Nine privately-owned domestic cats were anesthetized, and one testicle was surgically removed. An ejaculate was collected by electroejaculation, after which the remaining testicle was ectomized. There were no significant differences in the proportions of different sperm abnormalities between the cauda epididymidis removed before ejaculation and the one removed after ejaculation. A significantly (P = 0.009) higher proportion of spermatozoa with tail abnormalities was found in the ejaculates compared with the cauda epididymides (11.1 and 1.6%, respectively), while, as expected, there was a lower proportion of spermatozoa with distal droplets in the ejaculates than in the cauda epididymides (35.1 and 75.9%, respectively). This new information contributes to the understanding of the etiology of sperm defects in the domestic cat, and is of importance when evaluating a semen sample in this species.

Changes in semen quality and in vitro sperm capacitation during various frequencies of semen collection in dogs with both asthenozoospermia and teratozoospermia

Eight male dogs with both asthenozoospermia and teratozoospermia were used in this study. In experiment 1, semen was collected 10 times at intervals of 48 hr, 24 hr and 12 hr in 4 of the 8 dogs, and the semen quality was evaluated. In experiment 2, semen was collected 5 times at 24-hr intervals in the other 4 dogs. The spermatozoa collected on day 1 and day 5 were incubated for 4-6 hr in Canine Capacitation Medium, and the percentages of hyperactivated sperm (%HA), acrosome-reacted sperm (%AR), and the zona pellucida-binding sperm count (ZP sperm count) were assessed. The results of experiment 1 showed that the percentage of motile sperm increased and the percentage of abnormal sperm decreased markedly as the intervals between semen collections became shorter. When semen was collected at 12-hr intervals, the percentage of motile sperm increased from about 65%, the value before frequent collection was started, to about 80%, and the percentage of sperm with abnormal tails decreased from 30% to 15%. In experiment 2, the percentages of HA and AR, and the ZP sperm count in specimens collected on day 5 were higher than those in specimens collected on day 1, and the differences in % HA and in ZP sperm count were significant (P<0.05). The results demonstrated that sperm motility, abnormality, and potential fertility in dogs with asthenozoospermia and teratozoospermia can be temporarily improved by frequent semen collection.

Characterization of seminal plasma proteins and sperm proteins in ejaculates from normospermic bulls and bulls with thermally-induced testicular degeneration

Semen was collected from 5 mature beef bulls by electroejaculation before, during, and after 20 days of scrotal insulation. Thermally-induced testicular degeneration was irreversible in 3 of the bulls. Analysis of sperm and seminal plasma polypeptides revealed that 15 to 30 sperm polypeptides and 25 to 30 seminal plasma polypeptides were indistinguishable between bulls prior to the insulation treatment. Changes in the sperm polypeptides pattern appeared as early as 2 days after the insulation treatment and persisted for at least 11 months in 2 of the bulls. In the spermatozoa, there was a detectable loss of 31, 34, 49 and 58 kDa polypeptides and an appearance of 6 to 8 new major polypeptides, ranging from 32 to 83 kDa. The 83 kDa polypeptide was most prominent in the 2 bulls that regained normal sperm motility and morphology following the insulation period. The post-insulation appearance of a seminal plasma polypeptide (circa 60 kDa) was also identified in these 2 bulls. Seminal plasma polypeptides remained qualitatively unaltered by the insulation treatment in the 3 bulls with irreversible testicular degeneration.

Sperm morphology and fertility in A.I. bulls

Forty-seven A.I. bulls between 15 and 26 months of age, were used to study the relationship between sperm morphology in fresh semen and fertility (56-day non-return rate) in frozen semen following 11,749 inseminations. The sperm morphology was studied in two freezing operations/bull in a phase-contrast microscope and morphological abnormalities were recorded as a percentage of the total number of counted spermatozoa. Morphological categories used in this study were abnormal heads, detached heads, nuclear pouches, abnormal acrosomes, proximal cytoplasmic droplets, abnormal midpieces and abnormal tails. The greatest mean value recorded for the investigated categories was found for abnormal heads (3.8%) but the majority of morphological abnormalities only occurred in about 1% of all studied spermatozoa. Breed effects were found, with a somewhat higher incidence (p less than or equal to 0.05-0.01) of sperm abnormalities and poorer fertility among SRB than among SLB bulls. Despite the low frequency of sperm abnormalities, statistically significant (p less than or equal to 0.05-0.001) correlations were found between abnormal heads, nuclear pouches and proximal cytoplasmic droplets assessed in fresh semen and fertility (56-day non-return rate) of frozen semen.

Fertility effects of chromosome rearrangement (insertion 16) in Charolais cattle from Brazil

Insertion 16, a structural chromosome abnormality originated by three breaks in one autosome, was detected with familial recurrence in a Charolais cattle population. Due to the peculiar nature of Insertion 16, its effect on the fertility of the carriers was verified by various parameters. A total of 115 animals was karyotyped to learn the segregational behavior of the chromosome abnormality, and 1,354 females were studied to evaluate the reproductive efficiency of the propositi, a pair of chimeric bulls for insertion 16. Their fertility was observed and compared with that of three normal bulls. Analysis of the results revealed that insertion 15 segregates in the offspring of only one heterozygous proposita, without sex preference, and that the percentage of conceptions in the cows inseminated by the propositi was similar to the controls'; however, for each conception with the semen of the propositus in which the insertion segregated, 0.16 more inseminations were necessary than for the controls. Similarly, the deviation in the percentage of nonreturns after the first insemination (15.9%) and the frequency of abnormal oestrous cycles (10.3%) indicate reduced fertility in the propositus, which is related to early embryo mortality.

Testicular degeneration in a male goat. A case report

Semen samples from an 18-month-old infertile Lamancha buck contained less than 10% motile spermatozoa and a high incidence of morphological abnormalities. Degenerate detached heads, tightly coiled tails, and thickened midpieces were the prominent morphological defects, affecting 46%, 30%, and 15% of ejaculated spermatozoa, respectively. At necropsy, the diagnosis of testicular degeneration was made, characterized by focal, noninflammatory seminiferous tubule occlusion and mineralization, with a more generalized sloughing of tubular germinal epithelium. When examining spermatozoa morphology from various sites of the excurrent ducts, detached heads were readily seen in efferent duct fluid (> 30% incidence) and the coiled tails and other midpiece defects became prominent with passage through the caput epididymis.