The roles of the epididymis and prostasomes in the attainment of fertilizing capacity by stallion sperm

The male reproductive cycle of the brown basilisk Basiliscus vittatus (Squamata: Corytophanidae) from Tabasco, Southern Mexico

We used histological and morphometric methods to study the testis and associated glands, including the epididymis, ductus deferens, and renal sexual segment (RSS), of specimens of Basiliscus vittatus sampled from Tabasco, Mexico (17.5926° N, 92.5816° W). Samples were collected throughout 1 year, which included the dry (February to May) and rainy (June to January) seasons. Spermatogenesis in B. vittatus is active throughout the year, but a significant increase in the testicular volume, diameters of seminiferous tubules, height of the germinal epithelium, spermiogenesis, and released spermatozoa occur in the dry season. During the rainy season, all aforementioned parameters decreased except the secretory activity of the epididymis and the RSS, which increased concomitant with an increase of the spermatozoa population within the ductus deferens. These data strongly suggest that B. vittatus reproduce year-round, but males exhibit a peak in spermatogenic activity during the dry season and a peak in insemination and/or copulation at the beginning of the rainy season. We highlight the importance of analyzing not only the testis but also accessory ducts and glands when determining the reproductive cycles of reptiles. The reproductive cycle of B. vittatus is discussed in relation to the environmental conditions of Southern Mexico and is compared to that of other squamates.

Seasonal variations of the epididymis in donkeys (Equus asinus) with special reference to blood epididymal barrier

The epididymis, a key component of the male reproductive system, controls spermatozoa's maturation, fertility, and storage. The objective of this study is to evaluate the histological, ultrastructural, and immunohistochemical variations in the epididymis of donkeys that occur throughout the year. During the breeding season (spring) and nonbreeding seasons (summer, autumn, and winter), 20 epididymis were collected from adult, clinically healthy donkeys. Compared to non-breeding seasons, the epididymal duct displayed a more active lining epithelium and more sperm in the lumen during the breeding season. The epithelial height is the lowest and the lumen is the widest during the breeding season. Furthermore, the epididymal epithelium in the tail region exhibits undulations with polyps-like projections. The epididymal epithelium is composed mainly of the principal, basal, and dark cells. Tight junction between adjacent principal cells is more obvious in the breeding season as compared to the non-breeding seasons. However, intraepithelial lymphocytes, phagocytic, and other immune cells are more frequent in non-breeding seasons. β-catenin, which is a component of the adherent junctions between adjacent PCs, exhibits more immunoreactivity during the spring. On the other hand, iNOS, an indicator of oxidative stress, reacts positively during the summer. Additionally, during non-breeding seasons, autophagy was detected within the epididymal epithelium which may be linked to stress adaptation. In conclusion, our findings suggest that the histological and ultrastructural characteristics of the epididymal epithelium are more active during spring compared to other seasons of the year. RESEARCH HIGHLIGHTS: The study aimed to evaluate the histological, ultrastructural, and immunohistochemical variations in the blood epididymal barrier (BEB) and epididymal epithelium of donkeys that occur throughout the year. In comparison to non-breeding seasons, the epididymal duct displayed a more active lining epithelium and more sperm in the lumen during the breeding season. The epithelial height is the lowest and the lumen is the widest during the breeding season. The epididymal epithelium in the tail region exhibits undulations with polyps-like projections that increase the surface area. β-catenin, which is a component of the adherent junctions between adjacent PCs, exhibits more immunoreactivity during the spring. On the other hand, iNOS, an indicator of oxidative stress, reacts positively during the summer.

Motility-related microRNAs identified in pig seminal plasma exosomes by high-throughput small RNA sequencing

Boar fertility is a key determinant of the production efficiency of the whole pig breeding industry and boar sperm motility is the seminal parameter with the greatest impact on the fecundity of a sow. Exosomes are small, extracellular vesicles found in many body fluids. Seminal plasma exosomes, which are secreted by the epididymis, prostate, seminal vesicles, and testes, contain a large number of miRNAs, the types and levels of which can reflect the physiological state of source cells. It has been shown that the expression profile of seminal plasma exosomal miRNA differs between low-motility semen and normal semen. The aim of this study was to investigate the relationship between semen motility and exosomal miRNA profiles to obtain information that would allow to predict boar fertility, as well as contribute to the understanding of the mechanisms by which exosomal miRNAs regulate semen motility. Three high-motility (semen motility >90 %) and three low-motility (semen motility <80 %) semen samples were collected from Landrace and Yorkshire boars, respectively, and seminal plasma exosomes were extracted by ultracentrifugation. Exosome characterization was performed using transmission electron microscopy, NTA, and Western blot. The expression profiles of exosomal miRNAs associated with semen motility in the two boar breeds were subsequently determined by small RNA sequencing. The results showed that 297 known miRNAs and 295 novel RNAs were co-expressed in the four groups. Notably, six miRNAs (ssc-miR-122-5p, ssc-miR-486, ssc-miR-451, ssc-miR-345-3p, ssc-miR-362, and ssc-miR-500-5p) were found to be differentially expressed in both boar breeds. Enrichment analysis of the target genes of the differentially expressed miRNAs showed that they were mainly involved in biological processes such as regulation of transcription from RNA polymerase II promoter, regulation of gene expression, and intracellular signal transduction and signaling pathways such as the PI3K-Akt, MAPK, and Ras signaling pathways. The six differentially expressed miRNAs identified in this study have significant potential as noninvasive markers of boar semen motility. Meanwhile, the results of the enrichment analysis provide novel insights into the mechanisms underlying the regulation of semen motility.

Sperm Quality Assessment in Stallions: How to Choose Relevant Assays to Answer Clinical Questions

Stallion sperm analysis is indicated for infertility diagnosis, pre-sale expertise, production of fresh or frozen doses, and frozen straw quality control. Various collection methods are described, and numerous assays can be performed on semen. Determining an approach for each of these cases is challenging. This review aims to discuss how to obtain relevant clinical results, answering stallion owners' concerns. Semen can be collected with an artificial vagina on a phantom or a mare, by electro-ejaculation under anesthesia, or after pharmacological induction. The collection method influences the semen volume and concentration, while the total sperm number depends on the testicular production and collection frequency. In the seminal plasma, acidity, pro-oxidant activity, and some enzymes have repercussions for the semen quality and its conservation. Moreover, non-sperm cells of seminal plasma may impact semen conservation. Motility analysis remains a core parameter, as it is associated with fresh or frozen dose fertility. Computer-assisted motility analyzers have improved repeatability, but the reproducibility between laboratories depends on the settings that are used. Morphology analysis showing spermatozoa defects is useful to understand production and maturation abnormalities. Staining of the spermatozoa is used to evaluate viability, but recent advances in flow cytometry and in fluorochromes enable an evaluation of multiple intracellular parameters. Spermatozoa protein expression already has clinical applications, for example, as a fertility and freezing ability predictor. At present, stallion semen analysis ranges from macroscopic evaluation to assessing spermatozoa proteins. However, clinically, all these data may not be relevant, and the lack of standardization may complicate their interpretation.

A stallion spermatozoon's journey through the mare's genital tract: In vivo and in vitro aspects of sperm capacitation

Conventional in vitro fertilization is not efficacious when working with equine gametes. Although stallion spermatozoa bind to the zona pellucida in vitro, these gametes fail to initiate the acrosome reaction in the vicinity of the oocyte and cannot, therefore, penetrate into the perivitelline space. Failure of sperm penetration most likely relates to the absence of optimized in vitro fertilization media containing molecules essential to support stallion sperm capacitation. In vivo, the female reproductive tract, especially the oviductal lumen, provides an environmental milieu that appropriately regulates interactions between the gametes and promotes fertilization. Identifying these 'fertilization supporting factors' would be a great contribution for development of equine in vitro fertilization media. In this review, a description of the current understanding of the interactions stallion spermatozoa undergo during passage through the female genital tract, and related specific molecular changes that occur at the sperm plasma membrane is provided. Understanding these molecular changes may hold essential clues to achieving successful in vitro fertilization with equine gametes.

Efficiency of Ringer B. Braun solution on stallion epididymal sperm motility and viability compared to the commercial extender within 72 hours of storage

Collection of epididymal stallion sperm offers the opportunity to retain and use genetic material from the males after elective castration or even post mortem. The aim of the present study was to evaluate the effect of the Ringer B. Braun solution on stallion epididymal sperm viability and motility during liquid storage for 72 h at 4 °C and at 20 °C. Eight stallions (3–10 years old) were used in the study. Sperm from the cauda epididymis was harvested immediately after routine castration. The sperm from epididymis was washed out and diluted with Ringer B. Braun solution and with a commercial semen extender which was used as a control. Samples from each horse were divided into two parts: one part of samples was stored at 4 ± 1 °C as recommended for the commercial semen extender, the other one was stored at 20 ± 1 °C. Sperm viability, motility, and pH were checked one hour after collection and dilution, and after 24, 48 and 72 h of incubation. The results of sperm viability, subjective and progressive sperm motility showed slightly higher results in semen samples diluted with Ringer B. Braun solution in one hour compared to the commercial extender, by 2.40 ± 0.49% for viability (P > 0.05), by 0.30 ± 9.92% for subjective motility (P > 0.05) and by 5.70 ± 6.07% for progressive motility (P > 0.05). We suggest that Ringer solution could be used for a short term storage (1–24 h) of equine epididymal semen at a 4 °C temperature.

Epididymosomes: A potential male fertility influencer

During transit and storage in epididymis, spermatozoa undergo final maturation, acquire motility, functional competence and the ability to fertilise an oocyte. Epididymal secretions contain a complex biochemical milieu of diverse inorganic ions, proteins, metabolites and other molecules. Since it is believed that spermatozoa are translationally silent, proteins appearing in them are thought to be synthesised elsewhere, including epididymis, and then incorporated to the cells. One of the important mechanisms suggested to be involved in transfer of epididymal secretions to spermatozoa is through exosomes called epididymosomes. Epididymosomes released from the epididymal epithelium contain proteins, noncoding RNAs and distinct set of lipids that are transferred to spermatozoa while they pass through the different epididymal regions. Owing to the importance of these molecules for sperm maturation and fertilising ability, research on epididymosomes has gained increasing attention during the last decade. This review is focused on epididymosomes, with emphasis on recent advances in the understanding of mechanisms of epididymosomal cargo transfer to spermatozoa and potential roles of epididymosomes in sperm function and beyond. Possibilities of utilising the molecular signatures of epididymosomes as a tool for male fertility assessment are also discussed.

Morphological and histochemical changes in the dromedary camel epididymis in relation to reproductive activity

Environmental conditions such as temperature, light and food availability are known to influence the physiological status of animals. The male dromedary camel (Camelus dromedarius) is considered as a seasonal breeder with maximal sexual activity during certain period of the year followed by a decrease in activity during the remaining period. On the other hand, the male camel is also shown as an atypical seasonal breeder because this does not undergo sexual quiescence with complete cessation of spermatogenesis. This animal, however, shows remarkable physiological and behavioral changes during its maximal sexual activity. The annual breeding (rutting) period also influences the epididymis. In this review, an attempt has been made to present the available literature pertaining to gross anatomical, histological, histochemical, immunohistochemical and molecular changes in camel epididymis during breeding and nonbreeding periods, and the changes are believed to be correlated with male sexual behavior and libido. This review may also exhibit the dromedary camel breeding period, which is still unresolved, and thus may prove helpful in determining the exact time of mating, which is important for the success of assisted reproductive outcomes. Further, the review may contribute to a better understanding of the epididymal physiology in camel and may also prove useful in improving reproductive efficiency and population of this animal.

Multivariate models for estimating jackass semen production and quality

The purpose of this study was to analyse the effects of season, age, gonad and accessory sex glands on semen characteristics of jackass and to construct multivariate regression models to predict semen quality. In autumn, spring and summer, semen characteristics of 30 sexually mature donkeys (1,014 ejaculations) were analysed to investigate the effect of seasons on semen quality, and gonad and accessory sex gland parameters of 12 jackasses were measured immediately after ejaculation by ultrasonography to investigate the effect of seasons on reproductive organ size. Semen (598 ejaculates), gonad and accessory sex gland parameters of 40 jackasses aged between 3 and 7 years were analysed in autumn to investigate the effects of age and reproductive organ size on semen quality and to construct multivariate models. To verify the accuracy of the models, semen (476 ejaculates), gonad and accessory sex gland parameters of 20 jackasses were measured from March to June. Results revealed that semen, gonad and accessory sex gland parameters were not affected by season and age. Progressive motility (PM) was positively correlated with long axis of the spermatic cord (LASC) and negatively correlated with percentages of sperm abnormality (PSA). Total sperm count (TSC) was positively correlated with testis circumferences (TC) and cross-sectional area of cauda epididymis (CSACE). TC, CSACE, LASC and PSA were included into multivariate models to predict PM, TSC and functional sperm count (FSC) in 20 jackasses (PM = 72.332 + 0.428 LASC - 0.441 PSA; TSC = -169.929 + 8.728 TC + 0.253 CSACE; FSC = -206.645 + 8.788 TC + 0.258 CSACE). The predicted and observed values corresponded well. In conclusion, the tested models can be used for predicting semen quality of donkey.

A Higher Abundance of O-Linked Glycans Confers a Selective Advantage to High Fertile Buffalo Spermatozoa for Immune-Evasion From Neutrophils

The glycans on the plasma membrane of cells manifest as the glycocalyx, which serves as an information-rich frontier that is directly in contact with its immediate milieu. The glycoconjugates (GCs) that adorn most of the mammalian cells are also abundant in gametes, especially the spermatozoa where they perform unique reproduction-specific functions e.g., inter-cellular recognition and communication. This study aimed to implicate the sperm glycosylation pattern as one of the factors responsible for low conception rates observed in buffalo bulls. We hypothesized that a differential abundance of glycans exists on the spermatozoa from bulls of contrasting fertilizing abilities endowing them with differential immune evasion abilities. Therefore, we investigated the role of glycan abundance in the phagocytosis and NETosis rates exhibited by female neutrophils (PMNs) upon exposure to such spermatozoa. Our results indicated that the spermatozoa from high fertile (HF) bulls possessed a higher abundance of O-linked glycans e.g., galactosyl (β-1,3)N-acetylgalactosamine and N-linked glycans like [GlcNAc]1-3, N-acetylglucosamine than the low fertile (LF) bull spermatozoa. This differential glycomic endowment appeared to affect the spermiophagy and NETosis rates exhibited by the female neutrophil cells (PMNs). The mean percentage of phagocytizing PMNs was significantly different (P < 0.0001) for HF and LF bulls, 28.44 and 59.59%, respectively. Furthermore, any introduced perturbations in the inherent sperm glycan arrangements promoted phagocytosis by PMNs. For example, after in vitro capacitation the mean phagocytosis rate (MPR) rate in spermatozoa from HF bulls significantly increased to 66.49% (P < 0.01). Likewise, the MPR increased to 70.63% (p < 0.01) after O-glycosidase & α2-3,6,8,9 Neuraminidase A treatment of spermatozoa from HF bulls. Moreover, the percentage of PMNs forming neutrophil extracellular traps (NETs) was significantly higher, 41.47% when exposed to spermatozoa from LF bulls vis-à-vis the spermatozoa from HF bulls, 15.46% (P < 0.0001). This is a pioneer report specifically demonstrating the role of O-linked glycans in the immune responses mounted against spermatozoa. Nevertheless, further studies are warranted to provide the measures to diagnose the sub-fertile phenotype thus preventing the losses incurred by incorrect selection of morphologically normal sperm in the AI/IVF reproduction techniques.

Human prostasomes an extracellular vesicle - Biomarkers for male infertility and prostrate cancer: The journey from identification to current knowledge

Extracellular vesicles (EVs) are gaining attention among the cell biologists and researchers over the last two decades. Prostasomes are considered to be (Evs) secreted by prostate epithelial cells into the semen during emission or ejaculation. Prostasomes contain various proteins required for immune regulation namely, amino and dipeptidyl peptidase; endopeptidase (neutral); decay accelerating factor; angiotensin-converting enzyme. Sperm cells need a few prerequisites in order to fertilize the egg. The role of prostasomes in enhancing the male fertility was reviewed extensively throughout the manuscript. Also, prostasomes have an immunosuppressive, immunomodulatory, antibacterial role in the female reproductive tract, and in some cases they can be used as immunocontraceptive agent to regulate the fertility status. This review will give insights to many active researchers in the field of prostasomal research and male infertility/fertility research. This review will open many unanswered mechanisms of prostasomes with respect to structure-function analysis, fatty acids patterns in diagnosis as well as prognosis of male infertility/fertility. More scientific reports are in need to support the mechanism of prostasomes and its role in immunomodulation. The development of prostasomes as a biomarker for the prostate cancer is still miserable with a lot of controversial results by various researchers.

Immunohistochemical and Ultrastructural Features of the Seasonal Changes in the Epididymal Epithelium of Camel (Camelus dromedarius)

In order to evaluate the influence of reproductive activity on the functional role of the epididymal epithelium in the Egyptian dromedary camel, Connexin-43 (Cx-43), vascular endothelial growth factor (VEGF), and androgen receptor (AR) immunoreactivity in the epididymal epithelium and the fine structure of the principal, dark, basal, apical, and halo cells were investigated. The secretory activity of the principal cells was amplified in the breeding season, while its endocytotic function became more active in the nonbreeding season. This was evidenced by punctate strong immunoreactive signals for Cx-43, which appeared to be more intense in the apical region of these epithelial cells, and the extremely long slender stereocilia (microvilli) with multiple junctional complexes. The nonbreeding principal cells revealed granular immunoreactive signals for VEGF scattered in the apical and basal cytoplasm. Ultrastructurally, both extreme vacuolation and several multivesicular inclusion bodies were observed in their cytoplasm. Dark cell size greatly diminished in the nonbreeding season and their nuclear morphology greatly changed from oval to lobulated shape. The plasma membrane of the apical cells expressed several infoldings (microvilli) in the breeding season. However, it was almost smooth in the nonbreeding season except for a small microvillus that appeared as a bleb-like projection. In some regions, a strong dense immunoreactivity for VEGF could be recognized in the cytoplasm of the apical cells and some basal ones. Halo cells with numerous multivesicular inclusions occupying most of the cytoplasm and a lobulated eccentric nucleus were detected in the nonbreeding season. In conclusion, these findings indicate that the reproductive activity has a significant impact on the immunohistochemical and ultrastructural profiles of the epithelial cells lining the Egyptian dromedary camel epididymis.

Seasonal Variation of the Intraepithelial Gland in Camel Epididymis with Special Reference to Autophagosome

The key role of the epididymis is contributing to sperm storage, maturation, and survival. The epididymis of camel has a unique structure called the intraepithelial gland. The present work aimed to investigate the structure of the epididymal intraepithelial gland with special references to the seasonal variation. The samples were collected from the distal part of the corpus epididymes of completely healthy mature camels (Camelus dromedarius) in the breeding and nonbreeding seasons. Tomato lectin-positive material had been demonstrated within the epididymal spermatozoa. Here, we provide the first transmission electron microscopic study for the intraepithelial gland of camel epididymis detecting the autophagy during the nonbreeding season. The autophagosomes originated from the endoplasmic reticulum, surrounding mitochondria, and located mainly next to the basement membrane. This location is probably valuable for subsequent passing of their contents into the interstitium for possible recycling. The histochemical and ultrastructural characteristics of the gland in the breeding season indicated a hyperactive secretory microenvironment enriched with the glycoprotein-producing machinery, which could be controlled by androgens. The present data suggest that the camel intraepithelial gland has a significant impact on the reproductive activity through their secretory microenvironment during the breeding season. Moreover, it recycles the unused organelles or proteins for reuse or to supply energy under stress conditions in the nonbreeding season.

Comparison of the Effects of Five Semen Extenders on the Quality of Frozen-Thawed Equine Epididymal Sperm

Cryopreservation of epididymal sperm allows the saving of genetic material in case of unexpected death or emergency castration. The aim of the present study was the comparison of five different combinations of extenders commercially available for equine frozen semen processing for cryopreservation of epididymal sperm. Epididymal sperm were harvested from gonads of 10 healthy stallions after routine castration by retrograde flush technique. Then, samples were split and diluted with (1) INRA96 + INRA Freeze, (2) BotuSemen + BotuCRIO, (3) EquiPlus + Gent Freeze, (4) EquiPlus + EquiPlus Freeze, and (5) Gent + Gent Freeze. Extenders 1 and 2 showed higher values for total and progressive motility after thawing compared with extender 4 (P < .05). Extender 3 was in between 1 and 2 (P > .05), and extender 5 resulted in the lowest values (P < .05). The subpopulation of viable frozen-thawed sperm with high mitochondrial membrane potential and low intracellular calcium content was higher using extender 1 compared with extenders 3, 4, and 5 (P < .05) and higher in extender 2 compared with extenders 4 and 5 immediately after thawing (P < .05). After 1 hour of incubation, this subpopulation yielded the highest values in extender 2 (P < .05). Immediately after thawing, extender 1 yielded higher values for percentage of DFI and mean DFI than extenders 3, 4, and 5 (P < .05). Following 1 hour of incubation after thawing, sperm processed with extender 1 resulted in the highest values for percentage of DFI and mean DFI (P < .05). Using extender 2, mean DFI values were lower than those in extender 1 and higher than the extenders 3, 4, and 5 (P < .05). The study revealed that according to the examined sperm quality parameters, freezing extenders (extender 1, extender 2) using low concentrations of glycerol either combined with or without methylformamide were beneficial for cryopreservation of stallion epididymal sperm. For processing of stallion epididymal sperm, an extender containing milk proteins (extenders 1-4) for initial dilution after sperm harvesting is preferable to an extender including egg yolk (extender 5).

Determination of the activity and relative abundance of mRNA for antioxidant enzymes in stallion testicular and epididymal tissues: A comparison between two breeding seasons

The key prerequisite for successful insemination is sperm characterized to have positive values for morphological and biological variables which are determined by, among others, effective antioxidant protection during the lifespan of sperm cells. This study evaluated the activity and relative abundance of mRNA for antioxidant enzymes in stallion testicular and epididymal tissues during breeding (n = 5) and non-breeding (n = 5) seasons. The activity of superoxide dismutase (SOD) was greater (P < 0.05) during the breeding season, in particular in the testes and the caput epididymis, and SOD1 was the predominant isoform of the enzyme. The expression of the SOD3 gene was markedly less in the analyzed tissues, which indicates that this enzyme contributes to the antioxidant protection of the stallion reproductive tract. The activity of catalase (CAT) was less (P < 0.05) in the testes during both seasons while its relative abundances only during the breeding season. The greatest CAT activity was noted in the cauda epididymis during the breeding season. The activity of glutathione peroxidases (GPx) was greater (P < 0.05) in the testes than in other tissues and 10-fold greater during the breeding season. Similarly, relative abundance of GPx5 mRNA was greater (P < 0.05) in the caput epididymis than in the remaining tissues during both seasons. This study demonstrated that season has an ambiguous influence on the antioxidant defense system in stallion reproductive tissues. Seasonal differences in the present study, however, indicate that the reproductive system of stallions adapts well to environmental seasonal changes.

Boar seminal plasma exosomes maintain sperm function by infiltrating into the sperm membrane

Seminal plasma ingredients are important for maintenance of sperm viability. This study focuses on the effect of boar seminal plasma exosomes on sperm function during long-term liquid storage. Boar seminal plasma exosomes had typical nano-structure morphology as measured by scanning electron microscopy (SEM) and molecular markers such as AWN, CD9 and CD63 by western blot analysis. The effect on sperm parameters of adding different ratio of boar seminal plasma exosomes to boar sperm preparations was analyzed. Compared to the diluent without exosomes, the diluent with four times or sixteen times exosomes compared to original semen had higher sperm motility, prolonged effective survival time, improved sperm plasma membrane integrity (p < 0.05), increased total antioxidant capacity (T-AOC) activity and decreased malondialdehyde (MDA) content. The diluent containing four times concentration of exosomes compared to original semen was determined to inhibit premature capacitation, but not to influence capacitation induced in vitro. Inhibition of premature capacitation is likely related to the concentration of exosomes which had been demonstrated to transfer proteins including AWN and PSP-1 into sperm. In addition, using fluorescence microscopy and scanning electron microscopy analysis, it was demonstrated that exosomes in diluent were directly binding to the membrane of sperm head which could improve sperm plasma membrane integrity.

Ultrastructure of the male accessory glands of sesarmid crab, Parasesarma plicatum (Latreille, 1803)

The structure of accessory glands (AGs) in the male sesarmid crab, Parasesarma plicatum, is described by light and transmission electron microscopy. Adult males of carapace of width 1.6-2.2 cm were collected from along the estuarine regions of Kanyakumari District, India. Posteriorly, the male reproductive system receives several sac-like structures, referred to as AGs. Histologically, the AG is internally lined by cuboidal epithelium and the lumen encloses eosinophilic vesicular secretions, apparently glycopreoteinaceous in nature. Ultrastructurally, the epithelium shows the signs of typical infrastructure for synthetic activity, as demonstrated by the prolific presence of rough endoplasmic reticulum, free ribosomes, and Golgi complex. The cytoplasm is manifested with electron-dense, electron-lucent, and medium-density secretory vesicles, and the mode of release into the lumen is both merocrine and apocrine. Within the lumen, these secretory vesicles coalesce and aggregate into large heterogeneous masses of varying sizes, which may play an important role post-copulation within the female duct.

Characterization of proteolytic and anti-proteolytic activity involvement in sterlet spermatozoon maturation

In sturgeon, the acquisition of the potential for motility activation called spermatozoon maturation takes place outside testes. This process can be accomplished in vitro by pre-incubation of immature testicular spermatozoa in seminal fluid collected from fully mature Wolffian duct sperm. Addition of trypsin inhibitor to the pre-incubation medium disrupts spermatozoon maturation. There are no available data for the role of proteolysis regulators in fish spermatozoon maturation, while their role is recognized in mammalian sperm maturation. The present study evaluated the involvement of seminal fluid proteases and anti-proteolytic activity in the sterlet spermatozoon maturation process. Casein and gelatin zymography and quantification of amidase and anti-proteolytic activity were conducted in sturgeon seminal fluid from Wolffian duct sperm and seminal fluid from testicular sperm, along with spermatozoon extracts from Wolffian duct spermatozoa, testicular spermatozoa, and testicular spermatozoa after in vitro maturation. We did not find significant differences in proteolytic profiles of seminal fluids from Wolffian duct sperm and ones from testicular sperm. Zymography revealed differences in spermatozoon extracts: Wolffian duct spermatozoon extracts were characterized by the presence of a broad proteolytic band ranging from 48 to 41 kDa, while testicular spermatozoon extracts did not show such activity until after in vitro maturation. The differences in amidase activity coincided with these results. It may not be the levels of proteolytic and anti-proteolytic activity per se, but the alterations in their interactions triggering a cascade of signaling events, that is crucial to the maturation process.

Implication of the estrogen receptors GPER, ESR1, ESR2 in post-testicular maturations of equine spermatozoa

Estrogen receptors ESR1, ESR2 and GPER are present on mature ejaculated horse spermatozoa, suggesting these cells as putative targets for estrogens. Indeed, spermatozoa are exposed to high level of estrogens during the transit in the male and female genital tracts but their roles are not investigated. So, we evaluated in vitro the role of 17β-estradiol during post-testicular maturations: regulation of motility, capacitation and acrosome reaction. Moreover according to the pseudo-seasonal breeder status of the stallion, we analyzed the putative seasonal variations in the presence of ESRs in spermatozoa. We showed that ESRs are more present on stallion sperm during the breeding season. We showed that capacitation and acrosome reaction are independent of estradiol action in horse. Estradiol can weakly modulate the motility and this effect is strictly associated with GPER and not with ESR1 and ESR2. The subcellular localization of GPER in the neck on stallion sperm is coherent with this effect. It seems that estrogens are not major regulators of sperm maturations associated to mare genital tract, so they could act during the epididymal maturations.

Sperm Proteome Maturation in the Mouse Epididymis

In mammals, transit through the epididymis, which involves the acquisition, loss and modification of proteins, is required to confer motility and fertilization competency to sperm. The overall dynamics of maturation is poorly understood, and a systems level understanding of the complex maturation process will provide valuable new information about changes occurring during epididymal transport. We report the proteomes of sperm collected from the caput, corpus and cauda segments of the mouse epididymis, identifying 1536, 1720 and 1234 proteins respectively. This study identified 765 proteins that are present in sperm obtained from all three segments. We identified 1766 proteins that are potentially added (732) or removed (1034) from sperm during epididymal transit. Phenotypic analyses of the caput, corpus and cauda sperm proteomes identified 60 proteins that have known sperm phenotypes when mutated, or absent from sperm. Our analysis indicates that as much as one-third of proteins with known sperm phenotypes are added to sperm during epididymal transit. GO analyses revealed that cauda sperm are enriched for specific functions including sperm-egg recognition and motility, consistent with the observation that sperm acquire motility and fertilization competency during transit through the epididymis. In addition, GO analyses revealed that the immunity protein profile of sperm changes during sperm maturation. Finally, we identified components of the 26S proteasome, the immunoproteasome, and a proteasome activator in mature sperm.

Liquid storage of equine semen: Assessing the effect of d-penicillamine on longevity of ejaculated and epididymal stallion sperm

Short-term storage of equine sperm at 5°C in an extender containing milk and/or egg yolk components is common practice in the equine breeding industry. Sperm motility, viability, DNA integrity and, consequently, fertilizing ability decline over time, partly due to reactive oxygen species (ROS) generation. We investigated whether adding the anti-oxidant d-penicillamine to a commercial milk/egg yolk extender delayed the decrease in semen quality. Semen was recovered on four consecutive days from eight 3-year old Warmblood stallions. On day 5, seven of the stallions were castrated and sperm recovered from the caudae epididymides. Ejaculated samples were split, and one portion was centrifuged and re-suspended to reduce seminal plasma content. All samples were diluted to 50millionsperm/ml and divided into two portions, one of which was supplemented with 0.5mM d-penicillamine. After 48h, 96h, 144h and 192h storage, sperm motility was assessed by computer-assisted semen analysis (CASA), viability by SYBR14/PI staining, and DNA integrity using the sperm chromatin structure assay (SCSA). d-Penicillamine had no effect on motility of ejaculated sperm (P>0.05) but reduced total and progressive motility of epididymal sperm. Sperm chromatin integrity was not influenced by storage time, seminal plasma or d-penicillamine. In short, adding d-penicillamine to a commercial semen extender was neither beneficial nor detrimental to the maintenance of quality in ejaculated semen stored at 5°C. The negative effect on motility of epididymal sperm may reflect differences in (membrane) physiology of spermatozoa that have not been exposed to seminal plasma.

Prostasomes of canine seminal plasma - zinc-binding ability and effects on motility characteristics and plasma membrane integrity of spermatozoa

Prostasomes are small lipid membrane-confined vesicles that are involved in various fertilization-related processes. The aim of this study was to demonstrate canine seminal plasma prostasomes' ability to bind zinc ions, as well as examining their effects on sperm motility characteristics and plasma membrane integrity during cold storage. Ejaculates, collected from five cross-bred dogs (n = 50), were subjected to ultracentrifugation followed by gel filtration (GF) on a Superose 6 column. Prostasomes appeared as a single fraction in the elution profile. Transmission electron microscopy (TEM) analysis of canine prostasomes revealed the presence of membrane vesicles with diameters ranging from 20.3 to 301 nm. The zinc-affinity chromatography on a Chelating Sepharose Fast Flow - Zn(2 +) showed that from 93 to 100% of the prostasome proteins bind zinc ions (P(+) Zn). SDS-PAGE revealed that canine P(+) Zn comprised four protein bands, with low molecular weights (10.2-12 kDa). We have also shown a positive effect of prostasomes (p < 0.05), especially variant B (2% of total seminal plasma protein) on canine sperm motility parameters after 2 h storage at 5°C (TMOT%, 44.75 ± 5.18) and PMOT%, 12.42 ± 1.59) and VAP, VSL, VCL, when compared with Control (TMOT%, 7.30 ± 1.41 and PMOT%, 1.70 ± 0.42). Higher percentage of spermatozoa with intact plasma membrane (SYBR/PI dual staining) and intact acrosome (Giemsa stained), after 2 h storage at 5°C, was showed, in variant A (1.5% of total seminal plasma protein) and B, when compared with Control and variant C (2.5% of total seminal plasma protein). The prostasomes' effect on motility and plasma membrane integrity of canine cold-stored spermatozoa may be related to their ability to bind zinc ions and regulate their availability to the sperm.

The antioxidant system of sterlet seminal fluid in testes and Wolffian ducts

Oxidative stress is a possible source of spermatozoa function deterioration. Seminal fluid (SF) protects spermatozoa against reactive oxygen species (ROS) attack during development in testes and transit through the reproductive tract. Spermatozoa curvilinear velocity and percent of motile cells as well as changes in thiobarbituric acid-reactive substance (TBARS) content, superoxide dismutase, and catalase activity, and uric acid concentration in SF were evaluated in sterlet sperm collected from testes 24 h after hormone induction of spermiation and from Wolffian ducts at 12, 24, 36, and 60 h after hormone injection (HI). While testicular spermatozoa motility was not initiated in activating medium, Wolffian duct sperm showed low motility at 12 h, significant increase at 24 and 36 h, and decrease at 60 h. Testicular SF was characterized by the highest level of TBARS and activity of studied enzymes compared with SF from Wolffian duct sperm at 24 h post-HI. In fluid from Wolffian duct sperm, a significant increase in TBARS content was shown at 36-60 h post-HI. In contrast to testicular SF, in SF from Wolffian duct sperm, this increase was not counterbalanced by changes in the studied variables of antioxidant system. This may be the source of the observed decrease in spermatozoa motility parameters 60 h post-HI. The results may confirm a dual role of ROS in fish sperm physiology. The data with respect to decrease in sturgeon spermatozoa motility parameters at 60 h post-HI should be taken into account in artificial sturgeon propagation.

Enzymatic scavengers in the epididymal fluid: comparison between pony and miniature breed stallions

The use of stallion semen collected from cauda epididymis for AI has increased due to the new protocols available for cryopreservation. Preserving the genetic material from valuable males that suffer sudden death or other events that prematurely end the stallion's reproductive life is an important strategy for Stud breeding management. While protecting spermatozoa from oxidative stress and infectious agents, the epididymis promotes the enhancement of sperm cell morphology and changes in membrane protein profile, increasing its fertility potential. The epididymal fluid must be a balanced redox environment to allow sperm preservation and protein-protein and protein-lipids interactions to quantify. The aim of this study was quantify the enzymatic ROS scavengers in epididymal fluid of pony and miniature breed stallions. Epididymides from 8 pony stallions and 12 miniature breed stallions were dissected and fluid from caput, corpus and cauda epididymis collected. Spermatozoa were separated of epididymal fluid by 2-step centrifugation. The activities of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured and compared between stallion groups and epididymal regions. The three enzymes were present in all epididymal regions tested, with higher activities of catalase and SOD in cauda epididymis in miniature breed stallions (P<0.05). GPx activity was higher in caput epididymis in pony stallions (P<0.05), however with no difference to fluid from cauda epididymis of both breeds. These results show a difference in antioxidant enzymatic scavengers between pony and miniature breed stallions. Also, our data confirm the protective role of cauda epididymis, preserving spermatozoa integrity from oxidative damage. As glutathione peroxidase is involved in several signaling pathways, its constant activity during epididymal transit corroborates the importance of this enzyme for spermatozoa maturation.

Immunolocalization of insulin-like growth factor-I (IGF-I) and its receptors (IGF-IR) in the equine epididymis

Insulin-like growth factor plays a paracrine/autocrine role in regulating testicular function in the stallion, but its presence in the equine epididymis remains unknown. The aim of this study was to test the hypothesis that insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) are localized in the caput, corpus, and cauda of the epididymis in an age-dependent manner. Immediately after castration, epididymal tissue was fixed, paraffin-embedded, and processed for immunohistochemistry (IHC). Western blot was also performed using equine epididymal extracts to verify the specificity of the antibodies against IGF-I and IGF-IR. Immunolabeling of IGF-I was observed in the cytoplasm of principal and basal cells in the caput, corpus, and cauda at the pre-pubertal (3–7 months), pubertal (12–18 months), post-pubertal (2–4 years), and adult stages (4.5–8 years). Immunolabeling of IGF-IR was observed in the cytoplasm of principal cells in all regions of the epididymis in each age group. Immunolabeling of IGF-IR was also detected in the cytoplasm of basal cells from animals of all ages. Bands observed by Western blot corresponded to the molecular weights of IGF-I and IGF-IR, ~23 kDa and 95 kDa, respectively. These results suggest that IGF-I might function as an autocrine and/or paracrine factor during the development, maintenance and/or secretions of the stallion epididymis.

Influence of recovery method and centrifugation on epididymal sperm from collared peccaries (Pecari tajacu Linnaeus, 1758)

In order to establish protocols for gamete recovery from accidentally killed wild animals, or to take advantage of those slaughtered by captive breeders, we assess the influence of two methods on the recovery of epididymal sperm from collared peccaries, and verify the effect of centrifugation on such gametes. Genitalia from nine animals were used. For each animal, one epididymis was processed by flotation and the other was processed by retrograde flushing, both using a buffered media based on Tris. Following recovery, sperm were evaluated for motility, vigor, viability, functional membrane integrity, and morphology. A 1-mL aliquot of each sample was centrifuged, the supernatant removed, and the pellet suspended and evaluated as fresh samples. The sperm characteristics did not differ between the samples collected by flotation or retrograde flushing (P < 0.05). Centrifugation promoted an increase in head and tail defects, thus reducing the percentage of viable sperm (P < 0.05). No other parameter assessed for both methods was affected by centrifugation. In conclusion, epididymal sperm from collared peccaries can be efficiently collected through flotation or retrograde flushing, but not when either is followed by centrifugation.

Effect of Phaleria macrocarpa on Sperm Characteristics in Adult Rats

PURPOSE

The purpose of this study was to determine the effects of Phaleria macrocarpa (PM) on male fertility by assessing its effect on the sperm characteristics which included the sperm count, motility, viability and morphology.

METHODS

Eighteen male rats were equally divided into three groups. Each group of rats was orally supplemented for 7 weeks either with PM aqueous extract (240 mg/kg), distilled water (0 mg/kg) or testosterone hormone, Andriol® Testocaps™ (4 mg/kg) respectively. On the last day of supplementation period, the rats were sacrificed and sperm was obtained from cauda epididymis via orchidectomy. The sperm count, motility, viability and morphology were determined.

RESULTS

PM aqueous extract significantly increased (p<0.05) the percentage of sperm viability. However, there was no significant effect of PM on the percentage of both sperm motility and morphology. The mean of body weight declined significantly in rats supplemented with PM aqueous extract compared to control groups (p<0.05).

CONCLUSION

The results showed that PM significantly increased sperm viability without changing the sperm motility and morphology. Hence, this study suggests that PM offers an alternative way to improve male fertility by improving the sperm quality.

Proteomic characterization and cross species comparison of mammalian seminal plasma

Seminal plasma contains a large protein component which has been implicated in the function, transit and survival of spermatozoa within the female reproductive tract. However, the identity of the majority of these proteins remains unknown and a direct comparison between the major domestic mammalian species has yet to be made. As such, the present study characterized and compared the seminal plasma proteomes of cattle, horse, sheep, pig, goat, camel and alpaca. GeLC-MS/MS and shotgun proteomic analysis by 2D-LC-MS/MS identified a total of 302 proteins in the seminal plasma of the chosen mammalian species. Nucleobindin 1 and RSVP14, a member of the BSP (binder of sperm protein) family, were identified in all species. Beta nerve growth factor (bNGF), previously identified as an ovulation inducing factor in alpacas and llamas, was identified in this study in alpaca and camel (induced ovulators), cattle, sheep and horse (spontaneous ovulators) seminal plasma. These findings indicate that while the mammalian species studied have common ancestry as ungulates, their seminal plasma is divergent in protein composition, which may explain variation in reproductive capacity and function. The identification of major specific proteins within seminal plasma facilitates future investigation of the role of each protein in mammalian reproduction.

BIOLOGICAL SIGNIFICANCE

This proteomic study is the first study to compare the protein composition of seminal plasma from seven mammalian species including two camelid species. Beta nerve growth factor, previously described as the ovulation inducing factor in camelids is shown to be the major protein in alpaca and camel seminal plasma and also present in small amounts in bull, ram, and horse seminal plasma.

Triennial Reproduction Symposium: the obstacle course to successful establishment of pregnancy in domestic livestock species

The 2012 Triennial Reproduction Symposium (TRS), "Impediments to Fertility in Domestic Animals," was held immediately before the Joint Annual Meeting of the American Society of Animal Science, American Dairy Science Association, Canadian Society of Animal Science, Western Section of the American Society of Animal Science, and the Asociación Mexicana de Producción Animal in Phoenix, AZ, in July, 2012. The theme of the symposium highlighted key impediments or opportunities in the process of creating a pregnancy, beginning with male and female gametes and ending with a viable fetus. The 2012 TRS was designed to focus on areas of current and exciting investigation across a variety of species and to include 8 presentations from a mix of established and early-career scientists. The TRS was also the venue for presentation of the 2012 L. E. Casida Award for Graduate Education; the recipient was R. D. Randel (Texas A&M University). The symposium provided an excellent opportunity for reproductive biologists to consider the broad spectrum of factors that limit fertility in domestic species and contemplate the current status of knowledge relative to several of the significant obstacles to pregnancy.

Comparative transcriptome analysis of the accessory sex gland and testis from the Chinese mitten crab (Eriocheir sinensis)

The accessory sex gland (ASG) is an important component of the male reproductive system, which functions to enhance the fertility of spermatozoa during male reproduction. Certain proteins secreted by the ASG are known to bind to the spermatozoa membrane and affect its function. The ASG gene expression profile in Chinese mitten crab (Eriocheir sinensis) has not been extensively studied, and limited genetic research has been conducted on this species. The advent of high-throughput sequencing technologies enables the generation of genomic resources within a short period of time and at minimal cost. In the present study, we performed de novo transcriptome sequencing to produce a comprehensive transcript dataset for the ASG of E. sinensis using Illumina sequencing technology. This analysis yielded a total of 33,221,284 sequencing reads, including 2.6 Gb of total nucleotides. Reads were assembled into 85,913 contigs (average 218 bp), or 58,567 scaffold sequences (average 292 bp), that identified 37,955 unigenes (average 385 bp). We assembled all unigenes and compared them with the published testis transcriptome from E. sinensis. In order to identify which genes may be involved in ASG function, as it pertains to modification of spermatozoa, we compared the ASG and testis transcriptome of E. sinensis. Our analysis identified specific genes with both higher and lower tissue expression levels in the two tissues, and the functions of these genes were analyzed to elucidate their potential roles during maturation of spermatozoa. Availability of detailed transcriptome data from ASG and testis in E. sinensis can assist our understanding of the molecular mechanisms involved with spermatozoa conservation, transport, maturation and capacitation and potentially acrosome activation.

Histological and immunohistochemical studies on the epididymal duct in the dromedary camel (Camelus dromedarius)

This study was conducted to underscore the spatial distribution of some biologically active proteins within the epididymal duct in the dromedary camel. Paraffin-embedded sections from different regions of epididymis were stained by conventional histological techniques and by immunohistochemistry. A battery of primary antibodies against six proteins (S100, alpha smooth muscle actin [α-SMA], connexin-43 [Cx43], galactosyltransferase [GalTase], angiotensin converting enzyme [ACE], and vascular endothelial growth factor [VEGF]) were used. The epididymal epithelium consisted of five cell populations: principal, basal, apical, dark, and halo cells. The histochemical findings indicated the absence of binding sites for VEGF and Cx43. The principal cells (PCs) showed variable immunoreactivity (IR) for ACE, S100, and GalTase throughout the whole length of the duct. The apical surfaces of most PCs (at the caput) and some PCs (at the corpus) exhibited intense ACE-IR, whereas those at the cauda displayed alternating negative and strong immunostaining. Similarly, moderate S100-IR was found in cytoplasm and nuclei of all PCs at the caput, few PCs at the corpus, and several PCs alternating with negative PCs at the cauda. In contrast, only some PCs showed weak to strong GalTase-IR in different regions. Apart from negative to weak positive S100-IR, basal cells failed to show IR for all other proteins. Apical cells displayed strong IR for ACE, S100, and GalTase with some regional differences. The peritubular and vascular smooth muscle cells revealed strong α-SMA-IR in all regions. In conclusion, the spatial distribution of different proteins in camel epididymis showed similarities and differences to other mammalian species. The region-specific topographic distribution of different proteins and cell types might indicate that the caput and cauda are metabolically more active than that of the corpus.

Characteristics of donkey spermatozoa along the length of the epididymis

In mammals, the epididymis has numerous interrelated functions including absorptive and secretory activity that affect luminal environment and cell membrane, and the maturation and storage of sperm. Spermatozoa acquire their motility and fertilizing ability during their passage through the epididymis and the motility of epididymal spermatozoa should be a balance between the maturation of flagellum and the inhibition of the flagellar machinery. In this study maturational change in sperm characteristics were evaluated in the epididymis of donkey. Spermatozoa collected from four portions of the epididymis (head, cranial corpus, caudal corpus, tail) were compared before and after ejaculation for viability, mitochondrial activity, kinetic parameters, and morphology. A significant increase in the mitochondrial activity along the epididymis was reported, suggesting a possible involvement in the motion mechanism. This should be corroborated by the significant correlation between mitochondrial activity and the total and progressive motility and the increase in velocities of spermatozoa recorded by computer-assisted sperm analysis. The percentage of most of the abnormal spermatozoa were similar in all tracts, with a great variability between jackasses. Only the bent midpiece percentage decreased significantly along epididymis. A significant increase in the percentage of distal cytoplasmic droplets (DCD), and a simultaneous decrease in the proximal cytoplasmic droplets (PCD), was found. The DCD fell down after ejaculation suggesting the late loss of the cytoplasmic residual (DCD) in the donkey, as hypothesized in the stallion. Because the prevalence of PCD were similar in both tail epididymal and ejaculated spermatozoa, a defect of the maturative process in the PCD sperm should be speculated.