The HSP90AA1 sperm content and the prediction of the boar ejaculate freezability

In a previous study we reported that the immunolabelling of GLUT3, HSP90AA1, and Cu/ZnSOD proteins on boar sperm did not show differences between good and poor freezability ejaculates, in terms of a qualitative analysis based on location and reactivity of these proteins at 17 degrees C and at 240 min post-thaw. Since predicting the ejaculate freezability is considerably important in sperm cryopreservation procedures, the objective of the present study was to quantify the expression of these three proteins in good and poor freezability ejaculates. For this purpose, 10 ejaculates from 9 Piétrain boars were cryopreserved and their sperm quality assessed in the three main steps of the freezing process (17 degrees C, 5 degrees C, and 240 min post-thaw). After this assessment, the 10 ejaculates were clustered for freezability on the basis of their sperm progressive motility and membrane integrity at 240 min post-thaw. From the whole ejaculates, only four good and four poor freezability ejaculates displaying the most divergent values were selected for a western blot assay using sperm samples coming from the three mentioned freezing steps. Protein levels through densitometry were significantly different between good and poor freezability ejaculates for Cu/ZnSOD at 240 min post-thaw (P <or= 0.01) and for HSP90AA1 at 17 degrees C and 5 degrees C (P <or= 0.05). This last finding claims the introduction of tests based on molecular markers in spermatozoa to accurately predict the freezability of ejaculates in order to promote the use of frozen semen on artificial insemination programmes.

Fertility after post-cervical artificial insemination with cryopreserved sperm from boar ejaculates of good and poor freezability

This study compared the field fertility outcomes in frozen-thawed (FT) sperm from boar ejaculates with different freezability (good, GFE/poor, PFE) while testing the reliability of the post-cervical artificial insemination (post-CAI) in FT sperm. The assay was conducted over eight months with 86 weaned sows being inseminated by post-CAI. Every ejaculate in a total of 26 from 15 Piétrain boars was divided into a refrigerated semen portion (FS; control treatment) and a cryopreserved portion (FT sperm), and the ejaculates were in turn classified as GFE or PFE in function of the sperm progressive motility and viability at 240min post-thaw. As result, one of four possible treatments was randomly given to each sow: FS-GFE, FS-PFE, FT-GFE and FT-PFE. The number of pregnant and farrowing sows in FT-GFE did not significantly differ from those of FS control treatments. Contrarily, the probabilities of pregnancy were two times lower after inseminations with FT-PFE (P<0.05) compared to FT-GFE, which indicates that ejaculates with high post-thaw sperm progressive motility and viability are more likely to result in pregnancies than those with poor in vitro sperm function. There were no differences in litter size or the risk of backflow among treatments. Further trials are required to determine the optimal volume and concentration of FT sperm in post-CAI to obtain a more reliable method for farmers interested in cryopreserved sperm.

Effects of filtration through Sephadex columns improve overall quality parameters and "in vivo" fertility of subfertile refrigerated boar-semen

This study was performed to test the effects of filtration through several chromatographic resins on the semen quality parameters (percentages of viability, altered acrosomes and morphological abnormalities, motion characteristics and the response to the Osmotic Resistance Test) of boar ejaculates of poor quality. Our results indicate that filtration through a non-ionic Sephadex resin bed (Sephadex G-15), combined with a glasswool subjection bed, induced an overall improvement of semen quality parameters, especially seen in a significant (P<0.05) decrease in the percentages of morphological abnormalities and an increase of several motility parameters related to velocity and linearity. Similar results, although less intense, were observed when the filtration through G-15 resin was accompanied by an ionically neutral polypropylene disk bed instead of glasswool. On the other hand, filtration through two separate ion-exchange Sephadex resins, cationic C-50 and anionic A-50, have less beneficial, and even detrimental, effects on boar-semen quality. In all cases, filtration was accompanied by a significant (P<0.01) decrease in the final concentration of the samples. Ultrastructural and lectin studies showed that the interaction between sperm and chromatographic resins depends on the resin type utilized, and in the case of G-15 it seems that it works by trapping that sperm with not enough strength to overcome the physical resistance associated with chromatographic particles. When semen of poor quality was filtered through G-15 resin and then was utilized for "in vivo" fertility trials, a significant (P<0.05) increase in the percentage of fertility was observed, when compared with the same, but unfiltered, samples. In summary, our results strongly indicate that filtration through ionically inert, Sephadex chromatographic resins could be a very useful and practical method to improve both boar-semen quality and fertilizing ability, especially from mediocre and/or subfertile samples.

Boar spermatozoa and prostaglandin F2α

Prostaglandin F2alpha (PGF2alpha) has been used to improve reproductive performance in swine. The goal of the present work was to determine how the addition of PGF2alpha affects boar sperm quality. Eleven different treatments were evaluated: eight with only PGF2alpha (0.625, 1.25, 2.50, 5, 10, 12.50, 25 and 50mg PGF2alpha/100ml) and three binary treatments (0.625mg PGF2alpha/100ml+200microg/ml hyaluronic acid (HA), 1.25mg PGF2alpha/100ml+200microg/ml HA, 0.625mg PGF2alpha/100ml+7.5microM caffeine (Caf)). All these substances were added to 16 ejaculates from 16 healthy and sexually mature boars (n=16), and each ejaculate was considered as a replicate. Our study also assessed the effects of these 11 treatments over different periods of preservation. Sperm quality was tested immediately after the addition of treatments (time 0), and after 1, 3, 6 and 10 days of cooling at 15 degrees C. To evaluate sperm quality, five parameters were analysed: (1) sperm viability, acrosome and mitochondrial sheath integrity (using a multiple fluorochrome-staining test), (2) sperm motility, (3) sperm morphology and (4) agglutination (using a computer assisted system) and (5) osmotic resistance (using the ORT). Parametric (analysis of variance for repeated measures) and non-parametric tests (Friedman test) were used as statistical analyses. Treatments with PGF2alpha concentrations higher than 12.5mg/100ml were cytotoxic while the others did not damage boar spermatozoa. Thus, the other treatments may be used to produce profitable effects without adverse effects. Moreover, the addition of PGF2alpha at 5mg/100ml to sperm diluted in BTS may maintain sperm viability and motility better after 6 days of cooling, because significant differences were observed (P<0.05) compared with control at the same time.

Effects of filtration of semen doses from subfertile boars through neuter Sephadex columns

This study was designed to develop a method of improving the quality of sperm obtained from subfertile Piétrain boars. Seminal doses were filtered through neuter Sephadex columns (G-25 Medium, G-50 Fine, G-50 Medium and G-75, length 10 +/- 0.5 cm, flow rate 1 ml/20 s). Doses were prepared by pooling 10 ml semen samples collected from 58 asthenoteratospermic boars and diluted the sperm-cell rich fraction 1 : 6 in Betsville thawing solution extender. Sperm quality was determined before and after the filtering process. Sperm morphology and motility were assessed using the computer program SCA 2002 production, and sperm vitality was evaluated by fluorescence multistaining. ORT and HRT tests were used to determine the osmotic resistance of spermatozoa, and metabolic performance was assessed by measuring l-lactate production. Results indicate that the filtration process rendered increased proportions of mature spermatozoa and of viable spermatozoa with an intact acrosome, nucleus and mitochondrial sheath. Sperm filtration led to decreased percentages of spermatozoa with proximal and distal droplets and of agglutinated spermatozoa, along with slightly diminished ORT values. HRT scores and L-lactate production were unaffected. Our findings indicate that filtering through a Sephadex column improves the sperm morphology and vitality of seminal doses obtained from subfertile boars, but produces no functional changes in the spermatozoa. All four column types yielded similar results.

Effects of cryopreservation on semen quality and the expression of sperm membrane hexose transporters in the spermatozoa of Iberian pigs

This study evaluated the effects of cooling, freezing and thawing on the plasma membrane integrity, kinetics and expression of two sugar transporters glucose transporter-3 and -5 (GLUT-3 and GLUT-5) in spermatozoa from Iberian boars. Semen samples were collected twice weekly from eight young, fertile Iberian boars of the 'Entrepelado' and 'Lampiño' breeds. The samples were suspended in a commercial extender and refrigerated to 17 degrees C for transport to the laboratory (step A), where they were further extended with a lactose-egg yolk-based extender and chilled to 5 degrees C (step B) prior to freezing in the presence of glycerol (3%). Spermatozoa were assessed for plasma membrane integrity and sperm motility at each of the steps, including post-thaw (step C). Aliquots were also prepared for immunocytochemical localisation of the sugar transporters (fixed and thin smears for transmission and scanning electron microscopy levels respectively) and for SDS-PAGE electrophoresis and subsequent western blotting, using the same antibodies (rabbit anti-GLUT-3 and anti-GLUT-5 polyclonal antibodies). The results showed lower percentages of progressively motile spermatozoa at step C in both breeds, while the percentage of live spermatozoa was significantly lower only in the 'Entrepelado' breed. The results obtained from electron microscopy clearly showed that Iberian boar spermatozoa expressed the hexose transporters, GLUT-3 and GLUT-5. The pattern of expression, in terms of location and concentration, was characteristic in each case but, in the case of isoform GLUT-5, it remained constant during the different steps of freezing-thawing protocol. These results indicate that cryopreservation affects the status of sperm cells of Iberian boars by altering the distribution of some membrane receptors and decreasing the percentage values of parameters linked to sperm quality.

Hexose-specificity of hexokinase and ADP-dependence of pyruvate kinase play important roles in the control of monosaccharide utilization in freshly diluted boar spermatozoa

Incubation of boar sperm from fresh ejaculates in a minimal medium with 10 mM glucose induced a fast and intense activation of glycolysis, as indicated by the observed increases in the intracellular levels of glucose 6-phosphate (G 6-P) and ATP and the rate of formation of extracellular L-lactate. The effect of glucose was much more intense than that induced by fructose, sorbitol, and mannose. The greater utilization of glucose was related to a much greater sensitivity to hexokinase when compared with the other monosaccharides. Thus, the presence of 0.5 mM glucose induced total hexokinase activity in supernatants from sperm extracts of 1.7 +/- 0.1 mIU/mg protein, while the same concentration of both fructose, mannose, and sorbitol induced total hexokinase activity from 0.3 +/- 0.1 mIU/mg protein to 0.60 +/- 1 mIU/mg protein. Kinetic analysis of the total pyruvate kinase activity indicated that this activity was greatly dependent on the presence of ADP and also showed a great affinity for PEP, with an estimated Km in supernatants of 0.15-0.20 mM. Immunological location of proteins closely related to glycolysis, like GLUT-3 hexose transporter and hexokinase-I, indicated that these proteins showed the trend to be distributed around or in the cellular membranes of both head and midpiece in a grouped manner. We conclude that glycolysis is regulated by both the specific availability of a concrete sugar and the internal equilibrium between ATP and ADP levels. Furthermore, localization of proteins involved in the control of monosaccharide uptake and phosphorylation suggests that glycolysis starts at concrete points in the boar-sperm surface.

Effect of culture conditions on the obtention of boar epididymal epithelial cell monolayers

The goal of this study was to investigate the effect of the collagenase digestion time, the initial density of fragments and the culture temperature on the obtention of a boar epididymal epithelial cell culture, which is a useful methodology for the study of epididymal functions. A confluent monolayer of caput, corpus and cauda epididymal epithelial cells was only obtained when an adequate enzymatic digestion of the connective tissue surrounding the epididymal tubule was performed. For the correct digestion of caput and corpus fragments two collagenase digestions of 2 and 1h, respectively, were enough. Cauda fragments, however, needed two collagenase digestions of 3h each. A confluent monolayer of caput, corpus and cauda epididymal epithelial cells was obtained regardless of the initial density tested (15, 30, 60 and 90fragments/well). However, cultures originated from 15 and 30fragments/well showed higher cell concentration during the first 2 weeks of culture than cultures originated from 60 and 90fragments/well. A confluent monolayer of caput, corpus and cauda epididymal epithelial cells was obtained at both 32 and 37 degrees Celsius, but at 32 degrees Celsius cells grew very slowly and confluence was not reached until a week later than it was with cells growing at 37 degrees Celsius. In conclusion, we have observed that the time of digestion with collagenase is an important factor for the successful establishment of boar epididymal cell monolayers, and that the initial density of fragments and the culture temperature should be taken into account.

Study of the polyol pathway in the porcine epididymis

Concentrations of D-glucose, D-fructose and D-sorbitol were quantified in porcine epididymal fluid by spectrofluorimetric assays and aldose reductase (AR) and sorbitol dehydrogenase (SDH) were located immunohistochemically in the epididymal epithelium. Glucose and fructose concentrations were low (<1 mM) and decreased in the cauda whereas sorbitol concentration (4-7 mM) was rather uniform along the duct. AR was luminally located on microvilli in the caput and corpus with less presence distally and was present in the lumen. SDH was present apically and basally in epithelial cells throughout the epididymis and in the lumen. The observations are consistent with diffusion of circulating glucose into the lumen, its conversion via AR to sorbitol which accumulates in the lumen and the action of SDH on sorbitol to produce fructose. Sperm metabolism of glucose and fructose may explain their lower concentrations in the cauda and sorbitol could be a metabolic substrate or osmolyte required for volume regulation.

Structural and ultrastructural features of boar seminal vesicles

The morphological features of boar seminal vesicles were examined by light and transmission microscopy. Boar seminal vesicles consist of glandular tissue arranged in multiple lobules containing a system of ramified secretory tubules. The secretory tubules are composed of a mucosa formed by an epithelium and an underlying lamina propria and, are surrounded by a muscular layer. The epithelium is made up of columnar cells and occasional basal cells. Mast cells are frequently found among epithelial cells. Three types of columnar cells, considered different stages of the secretory cell cycle, are present: principal cells, clear cells and dense cells. Principal cells are functionally differentiated cells characterised by abundant mitochondria, great development of the rough endoplasmic reticulum and presence of secretory granules in their cytoplasm. The apical surface of many principal cells shows apical blebs filled with PAS-positive material. No acid mucosubstances are detected. Microvilli cover the apical surface except in the apical blebs. Dense cells, arranged between principal cells, are also functional differentiated cells but with signs of cellular degeneration. Clear cells are an initial differentiated stage of columnar cells and are characterised by the presence of a poorly developed rough endoplasmic reticulum and by the absence of secretory granules. Proliferating cells are present among columnar cells. Basal cells contain scarce cytoplasm, few organelles and no secretory granules. The lack of mitotic activity in these cells suggests that they do not act as precursors of columnar cells.

Concentrations of carnitine, glutamate and myo-inositol in epididymal fluid and spermatozoa from boars

This study examines the concentrations of carnitine, glutamate and myo-inositol in fluid and spermatozoa from six epididymal regions. Samples were taken from six post-pubertal boars, and the sperm concentration, the protein concentration in epididymal fluid and the concentrations of carnitine, myo-inositol and glutamate in the epididymal fluid and spermatozoa were analysed. In epididymal fluid the concentration of myo-inositol decreased in a proximo-distal direction, whereas intraluminal concentrations of L-carnitine and L-glutamate increased distally. As changes in the concentration of these solutes did not parallel changes in sperm concentration, this may reflect secretion or absorption of theses solutes. The sperm content of inositol fell as they moved from the distal caput whereas glutamate content increased from the distal caput to more distal regions and carnitine content remained unchanged during epididymal transit. This is the first attempt to elucidate the changes in the content of glutamate and inositol in epididymal spermatozoa of mammals and in the fluid from different epididymal regions of boars.

Structural and ultrastructural features of boar bulbourethral glands

The morphological features of boar bulbourethral glands were examined by light and transmission microscopy. Bulbourethral glands are compound tubuloalveolar glands surrounded by a capsule of dense connective tissue and arranged in multiple lobules formed by endpieces and excretory ducts. Endpieces and excretory ducts are both lined by a single epithelium of mucous cells with a basal nucleus. Epithelial cells accumulate secretory granules containing neutral and carboxylated acid mucosubstances and a small amount of sulphated acid mucosubstances. The ultrastructure of epithelial cells varies according to the secretory cycle. In initial stages, the cells show a columnar shape and secretory granules unevenly distributed in the cytoplasm. As the synthesis of mucosubstances progresses, the amount of the secretory granules increases and the cellular shape becomes pyramidal. Secretory granules can contain inclusions and present differences among them according to their different phases of formation. In pyramidal cells, secretory products are released into the lumen by a merocrine mechanism.

Effects of exposing boars to different artificial light regimens on semen plasma markers and “in vivo” fertilizing capacity

This study was designed to assess the effects of exposing boars to an artificial photoperiod on semen quality in terms of sperm concentration, sperm vitality, sperm motility and acrosome integrity. We also determined biochemical semen plasma variables, such as total protein concentration, phosphorylated tyrosine residues and fructose, glucose and sorbitol contents, along with their effects on the fertility, prolificacy and libido of the boars. Three groups of 10 males were kept for 3 months under experimental conditions of 24, 12 and 0 h of artificial light, and a constant temperature of 21 +/- 1 degrees C and 60-75% humidity. The animals were fed a nutritious diet and subjected to semen collection twice per week. Semen samples were analyzed throughout the entire experimental period. Our results indicate that, while the extreme photoperiods (0 and 24 h of light) affected semen quality in terms of sperm concentration, acrosome integrity and semen volume, its fertilizing capacity was only significantly reduced under conditions of absolute darkness. Sperm motility was found to be a poor indicator of fertilizing ability, while other sperm factors, such as acrosome integrity or other functional variables seemed to behave better. The photoperiod was found to affect the production of accessory sex gland secretions more than their composition. In addition, light effects on fertility, prolificacy and libido seemed to be achieved through independent mechanisms.

Evaluation of boar sperm maturation after co-incubation with caput, corpus and cauda epididymal cultures

Boar sperm from the proximal caput epididymis were co-incubated with 1, 4, 7, 10 and 14-day old caput, corpus and cauda epididymal cultures for 24, 48 and 72 h. Boar kidney epithelial cells (LLC-PK1) and ECM alone were used as negative controls. Sperm motility, morphology and membrane integrity were studied to evaluate boar sperm maturation in vitro. Our results showed that epithelial cell monolayers (10, 14-day old) create a suitable microenvironment for the survival of proximal caput sperm and the maintenance of sperm motility over a 72 h period. Moreover, corpus epididymal tubule fragments in culture (1, 4-day old) are capable of promoting the migration of the cytoplasmic droplet along the sperm tail after 24h of co-incubation.

Proliferation and apoptosis of spermatogonia in postpuberal boar (Sus domesticus) testes with spontaneous unilateral and bilateral abdominal cryptorchidism

Cryptorchidism is a frequent male sexual disorder in mammals, which affects the histology of the tunica propria, interstitial tissue, blood vessels, seminiferous epithelium and testis functioning. In this paper, proliferation and apoptosis were examined in the seminiferous epithelium of both testes from unaffected boars and from boars suffering unilateral and bilateral cryptorchidism. In germ cells, proliferation was studied using the immunohistochemical PCNA technique, and apoptosis was analysed by in situ TUNEL labelling. An index was obtained for the proliferation and apoptosis observed in seminiferous tubules. In abdominal testes the epithelium contained few spermatogonia and Sertoli cells. In the testes of unaffected boars, numerous spermatogonia proliferated, whereas in cryptorchid testes such proliferation was lower and the proliferation/apoptosis ratio diminished. In the unaffected group, the TUNEL-positive germ cells were spermatogonia and spermatocytes in different phases of meiosis. In abdominal testes, the TUNEL-positive germ cells were spermatogonia alone. The apoptosis index of both abdominal and scrotal testes was similar. In conclusion, spontaneous cryptorchid testes showed a lower rate of spermatogonia proliferation in the seminiferous epithelium.

Semen quality of postpubertal boars during increasing and decreasing natural photoperiods

The present study analyses the effects of increasing and decreasing photoperiods on the semen quality of 20 selected postpubertal Landrace boars. The boars were exposed, throughout 75 days, to increasing and decreasing photoperiods of natural light, a constant temperature of 21 +/- 1 degrees C and 60-70% of humidity, fed with a nutritious diet and, submitted to a rhythm of semen collection of twice a week. During the last 2 weeks of each treatment, semen samples were analysed and the parameters measured were: ejaculate volume and pH, sperm concentration, sperm production and the number of semen doses per ejaculate, sperm vitality, sperm motility, osmotic resistance of spermatozoa and sperm morphology. The comparative analysis between increasing and decreasing photoperiods indicated that the semen quality of boars exposed to a decreasing photoperiod was reduced as a consequence of decreases in sperm concentration, sperm production and the number of semen doses. There was no difference between increasing and decreasing photoperiods in terms of sperm vitality and sperm motility, nor in the osmotic resistance of spermatozoa to isotonic and hypotonic media. The analysis of sperm morphology showed significantly lower frequencies of mature and immature spermatozoa with a distal cytoplasmic droplet, and significantly higher frequencies of immature spermatozoa with a proximal droplet in boars exposed to the decreasing photoperiod. These results indicate that the sperm quality of the selected boars decreased during decreasing photoperiods, in comparison with increasing photoperiods, mainly due to impaired testicular function.

Effects of a high semen-collection frequency on the quality of sperm from ejaculates and from six epididymal regions in boars

This study examines the effect of semen-collection rhythm on the sperm maturation process in boar epididymis. Three post-pubertal boars were submitted to a high semen-collection frequency (stressed boars) during 4 days, and three males were kept as a control group (control boars). Semen samples coming from six epididymal regions and from the ejaculate of each male were evaluated for sperm concentration, sperm vitality, sperm motility and sperm morphology. In each epididymal region, either fluid resorption or fluid secretion was determined from the variation in sperm concentration. The pattern of fluid resorption-secretion along the epididymal duct differed significantly between the stressed and control boars. A high semen-collection frequency also affected the development of sperm motility and the sperm cytoplasmic droplet displacement along the epididymal duct. The incidence of some sperm abnormalities was also found to be higher in some epididymal regions and ejaculates of stressed boars. From the results of this study, it can be concluded that a high semen-collection frequency brings about an altered resorption and secretion pattern of the epididymal fluid, which results in defective sperm maturation and abnormal development of sperm motility.

Lectin histochemistry of the boar bulbourethral glands

The present study describes, for the first time, the glycosidic content of boar bulbourethral glands using lectin histochemistry. Fourteen horseradish peroxidase- or digoxigenin-labelled lectins with different carbohydrate specificities were used in samples obtained from 3 healthy Landrace boars. The results obtained indicate that endpiece and duct cells synthesize and secrete mainly O-glycoproteins with alpha- and beta-D-N-acetylgalactosamine, beta-D-galactose-beta(1-->3)-D-N-acetylgalactosamine, D-N-acetylglucosamine and neuraminic acid residues. Glycoproteins secreted by bulbourethral glands have a role in the protection and lubrication of the urethra. In addition, they may be also involved in the regulation of the sperm metabolic activity and in the maintenance of the structural integrity of acrosomal and plasma membranes.

Development of a protocol for multiple staining with fluorochromes to assess the functional status of boar spermatozoa

The aim of this study was to design a simple and reliable method for the simultaneous evaluation of the nucleus, the acrosome, and the mitochondrial sheath of boar spermatozoa. Sperm samples coming from healthy and sexually mature Pietrain boars were incubated with two nuclear fluorochromes--bis-benzamide specific for viable cells, and propidium iodide specific for nonviable cells--the fluorochrome Mitotracker Green FM specific for functional mitochondria, and the lectin Trypsin inhibitor from Soybean (SBTI) conjugated with the fluorochrome Alexa Fluor 488 specific for proacrosin. The results obtained from assessing the functional status of the spermatozoa using fluorochromes were compared with the conventional sperm parameters of sperm vitality using the eosin exclusion test (EE test), and sperm motility and morphology using the computer-assisted semen analyzer SCA 2002Producció. Applying the multiple staining test, it was found that the frequency of viable spermatozoa with intact acrosome and intact mitochondria was not different from the frequency of viable spermatozoa obtained with the EE test, and also correlated positively with the frequency of motile spermatozoa and the frequency of mature spermatozoa. Therefore, this technique is useful to characterize the status of boar spermatozoa by assessing the nuclear, acrosomal, and mitochondrial integrity. Moreover, it provides reliable diagnostic information about the fertility potential of boars.

The cycle of the seminiferous epithelium in Landrace boars

The present study describes the morphological features of the eight stages of the seminiferous epithelium in Landrace boars according to the tubular morphology method, as well as their relative frequency, length, and duration. In Landrace boars the pre-meiotic stages occupied the 31.9 +/- 19.9% of the spermatogenic cycle and had a total length of 1788.8 +/- 1153.0 microm and a duration of 2.78 days; they were mainly characterised by the presence of leptotene and pachytene spermatocytes and round spermatids. Meiotic stages, with a relative frequency of 16.4 +/- 6.8%, a length of 787.1 +/- 603.1 microm and a duration of 1.41 days, contained spermatocytes in advanced meiosis I and/or in meiosis II and elongating spermatids grouped in bundles. Post-meiotic stages occupied the 50.6 +/- 20.4% of the spermatogenic cycle and had a length of 2096.8 +/- 1175.0 microm and a duration of 4.37 days; the most important event of these stages was the spermiation, which included the complete remodelling of sperm head and tail and the releasing of spermatozoa into the lumen, as well as the formation of residual bodies. From data obtained we concluded that both germ cell associations of the stages maintain constant among Landrace boars, and that the relative frequency, length and duration of the stages were directly dependent of the cytological transformations on the seminiferous tubules.

Histochemical study of the interstitial tissue in scrotal and abdominal boar testes

The present study describes the glycosidic content of the interstitial tissue in testes from healthy boars and from unilateral and bilateral abdominal cryptorchid boars using lectin histochemistry. The Leydig cells of healthy boars contained glycans with fucosyl, mannosyl, glucosyl, neuraminic acid and galactosyl residues, which have structural and transport functions, and participate in androgen synthesis and in cell regulation. Unilateral cryptorchidism induced high glucosyl and low galactosyl content in the Leydig cells of scrotal testes, resulting in impaired androgen production. In abdominal testes, the Leydig cells exhibited increased amounts of glucosyl and reduced amounts of galactosyl and neuraminic acid residues, resulting in defective cell regulation and lack of androgen synthesis. In healthy boars, the extracellular glycans contained fucosyl, galactosyl, glucosyl and neuraminic acid residues, which confer viscoelasticity on the interstitial tissue and participate in substrate transport, hormone binding and cell-cell interaction. Unilateral cryptorchidism did not induce anomalies in extracellular glycans in scrotal testes, but unilateral and bilateral cryptorchidism resulted in an increased content of fucosyl and galactosyl, and a decreased content of glucosyl and neuraminic acid residues in abdominal testes, leading to reduced viscoelasticity and defective substrate transport across the extracellular matrix.

Morphological and histochemical characteristics of the lamina propria in scrotal and abdominal testes from postpubertal boars: correlation with the appearance of the seminiferous epithelium

This study was undertaken to investigate the morphological characteristics and lectin affinity of the testicular lamina propria in healthy boars and in unilateral and bilateral abdominal cryptorchid boars. The lamina propria of scrotal testes from healthy boars and unilateral cryptorchid boars was constituted by an innermost noncellular layer, the basal lamina, and by 2 layers of peritubular cells, each separated by a fibrous layer. The noncellular layers contained collagen fibres and glycoconjugates with abundant N-acetylgalactosamine, galactose, fucose, N-acetylglucosamine and neuraminic acid residues. The inner peritubular cell layer was composed of myoid cells, the outer layer of fibroblasts. In the abdominal testes of unilateral and bilateral cryptorchid boars, the lamina propria of nondegenerating and degenerating seminiferous tubules appeared thickened due to an increased content of collagen fibres and glycoconjugates. Glycoconjugates showed decreased amounts of fucose, neuraminic acid and galactose, and increased amounts of N-acetylglucosamine residues. The basal lamina formed infoldings toward the seminiferous epithelium and contained small cells. Both inner and outer peritubular cells were fibroblasts of immature appearance. In degenerated seminiferous tubules of bilateral cryptorchid boars, the lamina propria was composed of a thickened and collagenised basal lamina, without peritubular cells and with a low content of glycoconjugates. In scrotal testes, therefore, the lamina propria was implicated in tubular contractility and in mediating the communication and the substrate diffusion between seminiferous tubules and interstitial tissue. Cryptorchidism induced morphological and histochemical alterations in the lamina propria of abdominal testes, which may be linked to evidence from other studies of lack of tubular contractility and defective cell-cell communication and substrate diffusion. The severity of these anomalies correlated with the severity of Sertoli cell alterations.

Lectin affinity of the seminiferous epithelium in healthy and cryptorchid post-pubertal boars

The present study describes the sugar content of the seminiferous epithelium, using lectin histochemistry, in healthy boars and in boars with unilateral and bilateral abdominal cryptorchidism. In healthy boars the apical cytoplasm of Sertoli cells exhibited abundant glucosyl (Con A and WGA lectins), galactosyl (HPA, DBA, SBA and PNA lectins), and fucosyl (AAA lectin) residues. Spermatogonia and spermatocytes contained abundant glucosyl (Con A and WGA lectins) and fucosyl (AAA lectin) residues. In spermatids, galactosyl (SBA and PNA lectins) and glucosyl (Con A and WGA lectins) residues increased progressively throughout spermiogenesis, and fucosyl (AAA lectin) residues decreased. As compared with healthy boars, the scrotal testis of unilateral cryptorchid boars showed decreased amounts of fucosyl (AAA lectin) and galactosyl (HPA and DBA lectins) residues on the Sertoli cell apical cytoplasm; spermatocytes exhibited higher content of glucosyl (Con A lectin) residues and spermatids showed altered nature of glucosyl (Con A and WGA lectins) and galactosyl (SBA and PNA lectins) complexes. In abdominal testes of unilateral and bilateral cryptorchid boars, immature Sertoli cells and spermatogonia showed decreased fucosyl (AAA lectin), and increased glucosyl (Con A and WGA lectins) and galactosyl (SBA and PNA lectins) contents. These results suggest that the seminiferous epithelium of healthy boars has polarized activity with the apical compartment implicated in germ cell-Sertoli cell adhesion and interaction, in transport of ions, substrates and fluids, and in acrosomal differentiation. In scrotal testes, unilateral abdominal cryptorchidism could lead to defective germ cell-Sertoli cell adhesion, impaired acrosomal differentiation and increased ionic transport in the apical compartment of the seminiferous epithelium. Unilateral and bilateral cryptorchidism could induce increased ionic transport and membrane permeability in the seminiferous epithelium of abdominal testes.

Cytology of the interstitial tissue in scrotal and abdominal testes of post-puberal boars

The interstitial tissue of the testes from healthy boars, and unilateral and bilateral abdominal cryptorchid boars was examined by light and transmission electron microscopy. The left and right testes of healthy boars, and the left (scrotal) testis of unilateral cryptorchid boars had abundant mature Leydig cells, few fibroblasts and mast cells, scarce and small blood vessels, and little lymphatic areas. The right (abdominal) testis of unilateral cryptorchid boars contained abundant Leydig cells, fibroblasts and erythrocytes, scarce mast cells, and frequent blood vessels; Leydig cells exhibited either a mature but degenerative appearance or an immature appearance, and fibroblasts displayed immaturity signs. The interstitial tissue of the left (abdominal) testes of bilateral cryptorchid boars had small blood vessels surrounded by erythrocytes, lymphocytes, and few plasma cells, and abundant mature and immature Leydig cells, immature fibroblasts, and mast cells. Mature Leydig cells showed mid or advanced degeneration, and immature Leydig cells displayed either non-degenerative or degenerative patterns. The right (abdominal) testes of bilateral cryptorchid boars contained scarce immature Leydig cells in advanced degeneration, large fibrous and adipose areas, and blood vessels. These results indicated that unilateral abdominal cryptorchidism affect neither the structural nor the cytologic features of the interstitial tissue in scrotal testes. Unilateral and bilateral cryptorchidism induced abnormal differentiation of Leydig cells and fibroblasts leading to decreased steroid production and increased collagenization in abdominal testes.

Morphologic and histochemical study of blood capillaries in boar testes: effects of abdominal cryptorchidism

BACKGROUND

Few data exist about the features of testicular microvasculature under normal and pathologic conditions.

METHODS

The morphology and lectin affinity of testicular capillaries were examined in healthy boars and in unilateral and bilateral abdominal cryptorchid boars.

RESULTS

The capillaries of scrotal testes contained a) the endothelial layer formed by two cells, b) the basal lamina constituted by collagen fibers and glycoconjugates with fucosyl, galactosyl, glucosyl, and neuraminic acid residues, and c) the pericyte layer formed by a single cell. These components participated in substrate exchange between blood and testicular tissue. The abdominal testes showed increased numbers of capillaries, which could exhibit a mature appearance, but also angiogenic or degenerative patterns. Angiogenesis was manifested in interstitial capillaries and was characterized by a) proliferation of endothelial cells, b) decreased thickness and decreased content of collagen fibers and glycoconjugates in the basal lamina, and c) lack of pericytes. Degenerative capillaries lay in association with seminiferous tubules and showed a) pyknotic endothelial cells; b) thickening, collagenization, and altered glycoconjugate content in the basal lamina; and c) increased development of pericytes. The angiogenesis of interstitial capillaries resulted in high vascular permeability, and the degeneration of intertubular capillaries led to defective substrate exchange between blood and seminiferous tubules.

CONCLUSIONS

Unilateral abdominal cryptorchidism did not alter the morphology and function of capillaries in the scrotal testis. Unilateral and bilateral abdominal cryptorchidism resulted in increased numbers and abnormal morphology and function of capillaries in abdominal testes. The proliferation of interstitial capillaries correlated with the immaturity of Leydig cells, and the degeneration of intertubular capillaries correlated with the thickening of the lamina propria.

Characterization of the glycoconjugates of boar testis and epididymis

Lectin histochemistry was used to perform in situ characterization of the glycoconjugates present in boar testis and epididymis. Thirteen horseradish peroxidase- or digoxigenin-labelled lectins were used in samples obtained from healthy fertile boars. The acrosomes of the spermatids were stained intensely by lectins with affinity for galactose and N-acetyl-galactosamine residues, these being soybean, peanut and Ricinus communis agglutinins. Sertoli cells were stained selectively by Maackia ammurensis agglutinin. The lamina propria of seminiferous tubules showed the most intense staining with fucose-binding lectins. The Golgi area and the apical part of the principal cells of the epididymis were stained intensely with many lectins and their distribution was similar in the three zones of the epididymis. On the basis of lectin affinity, both testis and epididymis appear to have N- and O-linked glycoconjugates. Spermatozoa from different epididymal regions showed different expression of terminal galactose and N-acetyl-galactosamine. Sialic acid (specifically alpha2,3 neuraminic-5 acid) was probably incorporated into spermatozoa along the extratesticular ducts. These findings indicate that the development and maturation of boar spermatozoa are accompanied by changes in glycoconjugates. As some lectins stain cellular or extracellular compartments specifically, these lectins could be useful markers in histopathological evaluation of diseases of boar testis and epididymis.

Characterization of the glycoconjugates of boar testis and epididymis

Lectin histochemistry was used to perform in situ characterization of the glycoconjugates present in boar testis and epididymis. Thirteen horseradish peroxidase- or digoxigenin-labelled lectins were used in samples obtained from healthy fertile boars. The acrosomes of the spermatids were stained intensely by lectins with affinity for galactose and N-acetyl-galactosamine residues, these being soybean, peanut and Ricinus communis agglutinins. Sertoli cells were stained selectively by Maackia ammurensis agglutinin. The lamina propria of seminiferous tubules showed the most intense staining with fucose-binding lectins. The Golgi area and the apical part of the principal cells of the epididymis were stained intensely with many lectins and their distribution was similar in the three zones of the epididymis. On the basis of lectin affinity, both testis and epididymis appear to have N- and O-linked glycoconjugates. Spermatozoa from different epididymal regions showed different expression of terminal galactose and N-acetyl-galactosamine. Sialic acid (specifically alpha2,3 neuraminic-5 acid) was probably incorporated into spermatozoa along the extratesticular ducts. These findings indicate that the development and maturation of boar spermatozoa are accompanied by changes in glycoconjugates. As some lectins stain cellular or extracellular compartments specifically, these lectins could be useful markers in histopathological evaluation of diseases of boar testis and epididymis.

Ultrastructural study of the boar seminiferous epithelium: changes in cryptorchidism

The present study compares the ultrastructural features of Sertoli cells and germ cells between scrotal testes of healthy boars and abdominal testes of unilateral and bilateral cryptorchid boars. In healthy boars, spermatogonia are flat cells lying in close association with the basal lamina. As differentiation progresses, spermatogonia acquire an oval profile and lose their contact with the basal lamina. Spermatocytes are round cells moving from the basal compartment of the seminiferous epithelium to the luminal compartment. Spermatids exhibit complex morphological changes leading to the formation of spermatozoa. Sertoli cells extend from the basal lamina to the tubular lumen. The nucleus encloses fine euchromatin and one or two nucleoli; the nuclear envelope has a few deep infoldings. The lateral cell membranes form junctional specializations that constitute the blood-testis barrier. The cytoplasm encloses smooth endoplasmic reticulum, vesicles, aggregates, and scattered mitochondria. The seminiferous epithelium of abdominal testes from unilateral and bilateral cryptorchid boars contains few spermatogonia with an abnormal appearance; the alteration in germ cell number is more severe in the bilateral disease. In unilateral cryptorchid boars, spermatogonia appear as either large pyramidal cells or roundish cells; in bilateral cryptorchid boars, spermatogonia show roundish profiles and degenerative patterns. Abdominal testes of both unilateral and bilateral cryptorchid boars are constituted by immature Sertoli cells that show abnormal cytoplasmic content, defective development of the blood-testis barrier, and atypical nuclear appearance; in bilateral cryptorchid boars, immature Sertoli cells exhibit degenerative signs. At postpubertal age, unilateral and bilateral cryptorchidism induce total arrest of spermatogenesis at spermatogonial stage as a result of an abnormal differentiation of the Sertoli cells. Moreover, the degeneration of abdominal testes initiates earlier in bilateral cryptorchidism than in unilateral cryptorchidism.

Efficiency of the process of meiosis in scrotal testes of healthy boars and unilateral abdominal cryptorchid boars

Unilateral abdominal cryptorchidism has usually been correlated with abnormalities in the spermatogenic activity of the scrotal testis. The present study describes the effects of unilateral abdominal cryptorchidism on the meiotic process in scrotal testes from postpubertal boars. The percentage of primary spermatocytes, secondary spermatocytes, and round spermatids was evaluated in testicular smears from scrotal testes of healthy boars and of right-sided unilateral abdominal cryptorchid boars. As compared to the scrotal testes of healthy boars, the scrotal testes of unilateral abdominal cryptorchid boars showed low transformation from primary to secondary spermatocytes (meiosis I), but normal transformation from secondary spermatocytes to round spermatids (meiosis II). The data obtained indicate that spontaneous unilateral abdominal cryptorchidism on the right side induced partial arrest of spermatogenesis at the primary spermatocyte stage that was attributed to anomalies in Sertoli-cell activity. Abnormal paracrine signals from altered Sertoli cells could have resulted in either disturbed mitosis, which led to the formation of spermatocytes with an abnormal DNA content, or abnormalities in the metabolic activity and the organization of the cytoskeleton of primary spermatocytes.

Characterization of the semen quality of postpuberal boars with spontaneous unilateral abdominal cryptorchidism on the right side

In recent studies, we found that the ectopic testis from postpuberal boars with unilateral abdominal cryptorchidism does not produce sperm. Therefore, in these males, the seminal characteristics can be used as indicators of the activity of the scrotal testis and its epididymis and also the accessory glands. The semen quality (ejaculate volume, cell-rich fraction volume, sperm concentration, sperm vitality, sperm motility, sperm morphology and cephalic stability of spermatozoa) was evaluated in healthy postpuberal boars and in postpuberal boars with unilateral abdominal cryptorchidism on the right side. In comparison with the healthy boars, the unilateral abdominal cryptorchid boars showed a significant decrease of the ejaculate volume, sperm concentration and sperm motility. The low sperm concentration indicated that unilateral abdominal cryptorchidism severely impairs the sperm production of the scrotal testis. The decrease of ejaculate volume was attributed to an abnormal activity of the accessory glands. The alterations in sperm motility develop as a result of dysfunctions in the epididymal epithelium and/or the accessory glands. The sperm vitality, sperm morphology and cephalic stability of spermatozoa maintained normal values; therefore, at testicular level, despite the low sperm production, the germ cell differentiation is not disturbed. At epididymal level, the morphological maturation of spermatozoa is not altered.

Morphologic study of the testes from spontaneous unilateral and bilateral abdominal cryptorchid boars

Macroscopical and histological characteristics were examined in both testes from three healthy boars, three boars with unilateral abdominal cryptorchidism on the right side, and three boars with bilateral abdominal cryptorchidism. Abdominal cryptorchidism, unilateral and bilateral, provoked a significant decrease of the weight and volume of the ectopic testes. The scrotal testis of the unilateral cryptorchid boars showed an increase in its volume and weight. Cryptorchidism also induced abnormalities in the histological structure of seminiferous tubules, lamina propria, and interstitial tissue of the abdominal testes. The number of seminiferous tubules decreased; the seminiferous epithelium was constituted by few spermatogonia with an atypical pattern and by abnormal Sertoli cells. The lamina propria showed a variable degree of thickening and collagenization. The interstitial tissue was very developed but displayed a decrease in the Leydig cell population. These abnormalities were more critical in bilateral cryptorchidism than in unilateral cryptorchidism. The scrotal testis of the unilateral cryptorchid boars showed normal appearance, but a decrease of the number of seminiferous tubules was observed. Moreover, the seminiferous tubules showed impaired spermatid maturation. The alterations observed in the abdominal testes of the unilateral and bilateral cryptorchid boars were attributed to defective proliferation and differentiation of Sertoli cells and Leydig cells. The anomalies in the scrotal testis of the unilateral cryptorchid boars were due to disturbances in the Sertoli cell activity.

Unilateral spontaneous abdominal cryptorchidism: structural and ultrastructural study of sperm morphology

Sperm morphology of three healthy boars and three boars with spontaneous abdominal cryptorchidism in the right testis has been evaluated by light microscopy. For each boar, two ejaculates have been analysed, corresponding to semen collections at the ages of 6.5 months (first collection) and 8 months (seventh collection). A comparative study of the sperm malformations present in the seventh semen collection between the healthy boars and the unilateral abdominal cryptorchid boars has also been performed by light microscopy. Sperm malformations of the seventh semen collection from the unilateral abdominal cryptorchid boars have been examined by scanning and transmission electron microscopy. The frequency of mature spermatozoa, immature spermatozoa, aberrant spermatozoa and detached heads maintained normals values in the first and the seventh semen collection from the unilateral abdominal cryptorchid boars. The comparative study of sperm abnormalities in the seventh semen collection between the cryptorchid boars and the healthy boars indicated that the unilateral abdominal cryptorchid boars had a significantly higher frequency of primary abnormalities, and a significantly lower frequency of secondary abnormalities. Some primary abnormalities, such as crater defect, knobbed acrosome defect, nuclear crests and abaxial tails were only observed in the unilateral abdominal cryptorchid boars. It was concluded that unilateral abdominal cryptorchidism provokes disturbances in the late stages of spermiogenesis, at testicular level. Alterations in the sperm maturation process at epididymal level were not found.