Comparison of two methods for obtaining spermatozoa from the cauda epididymis of Iberian red deer

Collection of epididymal semen in the tomcat (Felix catus) by stereomicroscope-aided retrograde flushing (SARF) improves sample quality

In small and laboratory animals epididymal spermatozoa can be collected only by the mincing technique however, blood and cell debris contamination may adversely affect the quality of the samples. This study aimed at performing the retrograde flushing technique, for the first time, in the tomcat. In the first experiment attempts to insert a blunted needle into tomcats' ductus deferentes were made and the cannulation time and the success rate were recorded. In the second experiment, insertion of the needle into the ductus was carried out under a stereomicroscope for one testis, while the other was submitted to mincing for sperm recovery and the samples obtained from paired testes were compared. In the first study, only twenty-eight percent of the cannulation attempts were successful whereas in the second experiment, 91% of the deferentes were successfully cannulated: 80% of the ducts were cannulated in less than three minutes. The stereomicroscope-aided retrograde flushing samples showed significantly higher sperm viability, motility and velocities, as compared to those resulted from mincing. The domestic cat serves as a model for more than 36 species of wild felids; the developed stereomicroscope-aided retrograde flushing technique has the potential to become the gold standard method for harvesting spermatozoa of endangered species that have a small ductus deferens.

Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art

The collection of gametes from recently deceased domestic and wildlife mammals has been well documented in the literature. Through the utilization of gametes recovered postmortem, scientists have successfully produced embryos in 10 different wildlife species, while in 2 of those, offspring have also been born. Thus, the collection of gametes from recently deceased animals represents a valuable opportunity to increase genetic resource banks, obviating the requirement for invasive procedures. Despite the development of several protocols for gamete collection, the refinement of these techniques and the establishment of species-specific protocols are still required, taking into account both the limitations and the opportunities. In the case of wildlife, the optimization of such protocols is impeded by the scarcity of available animals, many of which have a high genetic value that must be protected rather than utilized for research purposes. Therefore, optimizing protocols for wildlife species by using domestic species as a model is crucial. In this review, we focused on the current advancements in the collection, preservation, and utilization of gametes, postmortem, in selected species belonging to Equidae, Bovidae, and Felidae, both domestic and wildlife.

Melatonin affects red deer spermatozoa motility and physiology in capacitating and non-capacitating conditions

Melatonin affects sperm physiology, possibly through membrane receptors. Effects were tested at low concentrations (1 pM, 100 pM, 10 nM and 1 µM) in red deer epididymal spermatozoa as a model for high-seasonality species. Samples were incubated with melatonin as uncapacitated or capacitating conditions (heparin) and evaluated for motility and physiology (flow cytometry). Most effects occurred at low concentrations (nM-pM), mainly protecting from apoptosis and maintaining acrosomal integrity, suggesting a role for membrane receptors rather than a direct antioxidant effect. Intracellular calcium was not affected, differing from other studies and perhaps because of the epididymal origin. This study supports the relevance of melatonin on sperm physiology and could contribute to the application of reproductive technologies in wild ruminants.

The influence of Percoll® density gradient centrifugation before cryopreservation on the quality of frozen wisent (Bison bonasus) epididymal spermatozoa

Background

The wisent (Bison bonasus) is a species that has undergone a population bottleneck. Homozygosity is prevalent within the population and may have a negative impact on semen quality in wisent bulls. Semen samples containing a large amount of functionally and morphologically impaired or dead spermatozoa have lower tolerance for cryopreservation process. Such samples are prone to involve damage acrosomes, to produce and release reactive oxygen which negatively affects proper function of spermatozoas. It is a good practice to select intact and viable gametes before subjecting the sample to cryopreservation to improve the efficiency of this process. The aim of this study was to assess the ability of Percoll® density gradient centrifugation in order to improve the quality of wisent spermatozoa after cryopreservation. Spermatozoa samples were analysed with computer-assisted semen analysis system and flow cytometry.

Results

Percoll® density gradient centrifugation resulted in increased percentage of motile spermatozoa, higher proportion of spermatozoa with normal morphology and proper functionality but also in a significant reduction of the total number of gametes. Nevertheless, the concentration of frozen spermatoza was still sufficient for obtaining a few complete insemination doses suggested for cattle from each epididymis.

Conclusions

While creating a high-quality genetic reserve, for in vitro fertilisation purposes, eliminating detritus and improving the overall quality of samples is more important than total number of spermatozoa. For these reasons, the achievement of higher post thaw quality of spermatozoa justifies the purification of samples by centrifugation in a Percoll® density gradient prior to the cryopreservation process.

Bos taurus and Cervus elaphus as Non-Seasonal/Seasonal Models for the Role of Melatonin Receptors in the Spermatozoon

Melatonin is crucial in reproduction due its antioxidant, hormonal, and paracrine action. Melatonin membrane receptors (MT₁/MT₂) have been confirmed on spermatozoa from several species, but functionality studies are scarce. To clarify their role in ruminants as reproductive models, bull (Bos taurus, non-seasonal) and red deer (Cervus elaphus, highly seasonal) spermatozoa were analyzed after 4 h of incubation (38 °C, capacitating media) in 10 nM melatonin, MT₁/MT₂ agonists (phenylmelatonin and 8M-PDOT), and antagonists (luzindole and 4P-PDOT). Motility and functionality (flow cytometry: viability, intracellular calcium, capacitation status, reactive oxygen species (ROS) production, and acrosomal and mitochondrial status) were assessed. In bull, MT₁ was related to sperm viability preservation, whereas MT₂ could modulate cell functionality to prevent excess ROS produced by the mitochondria; this action could have a role in modulating sperm capacitation. Deer spermatozoa showed resistance to melatonin and receptor activation, possibly because the samples were of epididymal origin and collected at the breeding season's peak, with high circulating melatonin. However, receptors could be involved in mitochondrial protection. Therefore, melatonin receptors are functional in the spermatozoa from bull and deer, with different activities. These species offer models differing from traditional laboratory experimental animals on the role of melatonin in sperm biology.

Freezing Protocol Optimization for Iberian Red Deer (Cervus elaphus hispanicus) Epididymal Sperm under Field Conditions

Creating germplasm banks of wild species, such as the Iberian red Deer (Cervus elaphus hispanicus) can be challenging. One of the main difficulties is the obtention and cryopreservation of good-quality reproductive cells when the spermatozoa are obtained from epididymides after death. To avoid a loss of seminal quality during transport, developing alternative methods for cooling and freezing sperm samples under field conditions is necessary. The objective of this study was to evaluate the effects of different durations of equilibrium and different techniques of cooling and freezing on Iberian red deer epididymal sperm quality after thawing to optimize the processing conditions in this species. Three experiments were carried out: (I) evaluation of refrigeration in straws or tubes of 15 mL; (II) study of equilibration period (0, 30, 60, or 120 min); and (III) comparison of four freezing techniques (liquid nitrogen vapor in a tank (C), liquid nitrogen vapor in a polystyrene box (B), dry ice (DY), and placing straws on a solid metallic plate floating on the surface of liquid nitrogen (MP)). For all experiments, sperm motility and kinematic parameters, acrosomal integrity, sperm viability, mitochondrial membrane potential, and DNA integrity were evaluated after thawing. All statistical analyses were performed by GLM-ANOVA analysis. Samples refrigerated in straws showed higher values (p ≤ 0.05) for mitochondrial activity and lower values (p ≤ 0.05) for apoptotic cells. Moreover, the acrosome integrity showed significant differences (p ≤ 0.05) between 0 and 120 min, but not between 30 and 60 min, of equilibration. Finally, no significant differences were found between freezing in liquid nitrogen vapors in a tank or in a box, although there was a low quality after thawing when the samples were cryopreserved in dry ice or by placing straws on a solid metallic plate floating on the surface of liquid nitrogen. In conclusion, under field conditions, it would be possible to refrigerate the sperm samples by storing them in straws with a 120 min equilibration period and freezing them in liquid nitrogen vapors in a tank or box.

The frequency of morphological defects of epididymal sperm in exotic animal species of the family Bovidae kept in the Czech Republic

Epididymal sperm morphology was evaluated by strict criteria using the DeSMA software. A total of 134 animals from the Dvůr Králové ZOO were included in the study. The aim of this study was to determine the prevalence of morphological defects of epididymal sperm in animals of the family Bovidae in species that are not native to the Czech Republic and are bred here only in zoos. Our results showed that the frequency of abnormalities was higher in exotic species of the Bovidae family compared to domestic species. Furthermore, the acquired defects prevailed over developmental abnormalities. Cytoplasmic droplets are a characteristic feature of epididymal sperm. Their average prevalence in the whole Bovidae family is almost 30%. However, distal droplets are not considered to be sperm pathology and, therefore, they are not the most frequent defect. The most common abnormalities are acquired head defects, followed by acquired tail defects, and then by acquired neck defects, mainly represented by proximal cytoplasmic droplets. The lowest prevalence was found for developmental abnormalities, with heads being more often affected than tails. The remaining defects were sporadic.

Long-Term Administration of Abacavir and Etravirine Impairs Semen Quality and Alters Redox System and Bone Metabolism in Growing Male Wistar Rats

Highly active antiretroviral therapy (HAART) is used in HIV-infected patients. Alongside the prolongation of patients' life, adverse side effects associated with long-term therapy are becoming an increasing problem. Therefore, optimizing of HAART is extremely important. The study is aimed at evaluating the toxicity of abacavir and etravirine in monotherapy on the reproductive system, liver, kidneys, and bones in young, sexually mature, male rats. Thirty-six 8-week-old male Wistar rats randomized into three 12-animal groups received either normal saline (control), abacavir 60 mg/kg (AB group), or etravirine 40 mg/kg (ET group) once daily for 16 weeks. Semen morphology, oxide-redox state parameters (MDA, SOD, catalase, GPx, glutathione, GSH/GSSG ratio) in tissue homogenates (testes, liver, kidneys), and serum samples were studied. In bones, microcomputed tomography and a four-point bending test were performed. Total sperm count, sperm concentration, motility, and sperm morphology did not differ significantly in AB or ET groups compared to the control. In the flow cytometry of semen, an increased percentage of cells with denatured DNA was noticed for both tested drugs. However, no significant changes of oxide-redox state in testicular homogenates were found, except of increased SOD activity in the AB-receiving group. Additionally, ET significantly altered catalase and GPx in the liver and SOD activity in kidneys. Abacavir decreased catalase in the liver and GSH levels in kidneys. AB caused significant changes to bone microarchitecture (bone volume fraction, trabecular number, connectivity density, total porosity) and increased Young's modulus. Etravirine had a greater impact on macrometric parameters of bones (tibial index, mid-tibial diameter, femur length). After 4 weeks in the ET group, a lower 1,25-dihydroxyvitamin D₃ serum concentration was found. The results showed that abacavir and etravirine disturb oxidative stress. An increase in the percentage of sperms with chromatin damage suggests decreased fertility in rats receiving the studied drugs. Both drugs affected bone formation in growing rats. Additionally, etravirine disturbed vitamin D metabolism.

Assessment of tebuconazole exposure on bovine testicular cells and epididymal spermatozoa

This study is the first to investigate the effects of tebuconazole (TEB) on the physiological functions of bovine testicular cells and epididymal spermatozoa. Motility and plasma membrane integrity of spermatozoa exposed to TEB (0.001-100 µM) were evaluated at different incubation times (0-6 h), while TEB-induced spermiotoxicity was assessed after 24 h in cell cultures. Testicular cells, obtained from the parenchyma of bovine testes, were seeded at 1.0 × 104 and 1.5 × 106 cells/well in 96- and 12-well culture plates and incubated for 48 h in culture media containing TEB (0.001-100 µM) to evaluate cytotoxicity and hormone release, respectively. TEB did not affect the motility and plasma membrane integrity. However, significant spermiotoxicity occurred at higher TEB (1-100 µM) concentrations (P < 0.05) compared to control and lower doses. Although no dose caused cytotoxicity in testicular cells (P > 0.05), 1 and 100 µM TEB caused a significant increase in testosterone secretion (P < 0.05). As a result, high doses of TEB (1-100 µM) had slightly suppressive effects on spermatozoa; however, these doses had stimulatory effects on testosterone secretion by testicular cells. It appears that the disruption of hormonal homeostasis of testicular cells after TEB exposure may result in metabolic and especially reproductive adverse effects in bulls.

Oocyte vitrification induces loss of DNA methylation and histone acetylation in the resulting embryos derived using ICSI in dromedary camel

Oocyte cryopreservation has become an important component of assisted reproductive technology with increasing implication in female fertility preservation and animal reproduction. However, the possible adverse effects of oocyte cryopreservation on epigenetic status of the resulting embryos is still an open question. This study evaluated the effects of MII-oocyte vitrification on gene transcripts linked to epigenetic reprogramming in association with the developmental competence and epigenetic status of the resulting embryos at 2-cell and blastocyst stages in dromedary camel. The cleavage rate of vitrified oocytes following intracytoplasmic sperm injection was significantly increased compared with the control (98.2 ± 2 vs. 72.7 ± 4.1%, respectively), possibly due to the higher susceptibility of vitrified oocytes to spontaneous activation. Nonetheless, the competence of cleaved embryos derived from vitrified oocytes for development to the blastocyst and hatched blastocyst was significantly reduced compared with the control (7.7 ± 1.2 and 11.1 ± 11.1 compared with 28.1 ± 2.6 and 52.4 ± 9.9%, respectively). The relative transcript abundances of epigenetic reprogramming genes DNMT1, DNMT3B, HDAC1, and SUV39H1 were all significantly reduced in vitrified oocytes relative to the control. Evaluation of the epigenetic marks showed significant reductions in the levels of DNA methylation (6.1 ± 0.3 vs. 9.9 ± 0.5, respectively) and H3K9 acetylation (7.8 ± 0.2 vs. 10.7 ± 0.3, respectively) in 2-cell embryos in the vitrification group relative to the control. Development to the blastocyst stage partially adjusted the effects that oocyte vitrification had on the epigenetic status of embryos (DNA methylation: 4.9 ± 0.4 vs. 6.2 ± 0.6; H3K9 acetylation: 5.8 ± 0.3 vs. 8 ± 0.9, respectively). To conclude, oocyte vitrification may interfere with the critical stages of epigenetic reprogramming during preimplantation embryo development.

Vitrification of camel oocytes transiently impacts mitochondrial functions without affecting the developmental potential after intracytoplasmic sperm injection and parthenogenetic activation

Oocyte vitrification preserves the female genetic resources of elite dromedary camels. In the current study, we aimed to explore the effects of vitrification of camel oocytes on mitochondrial activity, redox stress, and expression of genes related to mitochondrial function, apoptosis, pluripotency, and cytoskeleton. Moreover, we investigated developmental competence of vitrified oocytes after parthenogenetic activation. Oocytes vitrified with the Cryotop method were compared with the fresh oocytes. Our results showed that vitrification led to increased ROS production in oocytes as evidenced by an increase in the DCFDHA fluorescence intensity, and lower mitochondrial activity. At the molecular level, vitrification reduced mRNA expression of many genes, including those related to mitochondrial function (TFAM, MT-CO1, MFN1, ATP1A1, NRF1), pluripotency (SOX2 and POU5F1), and apoptosis (p53 and BAX). In contrast, expression of KLF4 and cytoskeleton-related genes (ACTB and KRT8) was not affected. However, we found no difference in the rates of oocyte survival, cleavage, and blastocyst development, and blastocyst hatching between fresh and vitrified oocytes after warming. Our results indicate that although vitrification of camel metaphase II (MII) oocytes adversely affected mitochondrial functions, the effect was transient without compromising the developmental potential of the oocytes after parthenogenetic activation.

Effect of Toxoplasma gondii on Ram Sperm Quality After Experimental Infection

The aim of this study was to investigate the effect of experimental Toxoplasma gondii infection on ram sperm quality. Five months old, pre-pubertal, rams were divided into four groups (n = 8 per group). Group A was the control group; the remaining animals received per os (p.o.) 5000 oocysts per ram. Group B did not receive treatment post-infection (p.i.). Group C received sulphadimidine (intermuscular injection (i.m.) 33 mg/kg for eight days; every 48 hrs) two months p.i. and Group D received the same drug twice (24 hours p.i. and two months later). Blood samples were collected every 15 days to detect serum immunoglobulin G (IgG). Epididymal sperm samples were analyzed for concentration, kinetics, morphology/viability, functional membrane integrity, DNA integrity, and the presence of parasite DNA. Histopathological examination was performed on the testes. The IgG titres in infected groups raised two weeks p.i. and remained high for four months. Higher values were noticed in viability and functional membrane integrity in positive spermatozoa in the control group compared to other groups, level of significance p < 0.05. Abnormal sperm was higher in groups C and D vs. A and C vs. B (p < 0.05). T. gondii DNA was detected in three sperm samples of the infected rams (12.5%). Histopathology revealed similar findings with little variation among all infected groups, characterized mostly by increased interstitial connective tissue, non-purulent inflammation, and presence of seminiferous tubules with spermatogenic cell depletion, which increased gradually from D to C and B groups. In conclusion Toxoplasmosis in pre-pubertal age negatively affected mature ram sperm quality, while sulphadimidine administration failed to alter this.

Eficiência de duas técnicas de recuperação de espermatozoides epididimários de cães e avaliação seminal pós-criopreservação

RESUMO O objetivo deste trabalho foi avaliar a recuperação de espermatozoides epididimários de cães castrados, utilizando as técnicas de fluxo retrógrado (FR) e flutuação (FL) em diluidor Tris-gema, antes e após a criopreservação. Foram coletados 30 complexos testículo-epididímos (CTE), sendo 15 para FR e 15 para FL, e, logo após a recuperação dos espermatozoides, foram analisadas as alterações morfológicas nessas células espermáticas. Após a adição do diluidor, foram avaliados os parâmetros de motilidade total (MOT) e vigor (V) espermáticos. O sêmen pós-criopreservado foi submetido ao teste de termorresistência nos tempos T0, T30, T60 e T90 minutos, além da avaliação das membranas plasmática e acrossomal por sondas fluorescentes. Não houve diferença estatística entre as técnicas quanto à MOT e ao vigor no sêmen diluído (FR-MOT: 82,3% e V: 3,4; FL-MOT: 79,6% e V: 3,2) e pós-criopreservado (FR-MOT: 34% e V: 2,8; FL-MOT: 30% e V: 2,7). A partir do T30, houve diferença significativa quanto à MOT e ao vigor nas técnicas utilizadas, e o tempo também prejudicou o acrossoma espermático a partir do T30. Conclui-se que as técnicas de recuperação de espermatozoides epididimários de cães castrados, testadas neste trabalho, podem ser utilizadas para refrigeração e criopreservação de sêmen.

Bovine epididymal spermatozoa treatment for in vitro fertilization: Heparin accelerates fertilization and enables a reduction in coincubation time

This study aimed to establish a protocol for in vitro embryo production using epididymal sperm (EP). Samples were obtained from ejaculated sperm (EJ) and the epididymis of 7 Gir bulls. First, the effect of heparin (+) on the viability, longevity (Experiment 1) and fertilization rates (Experiment 2) of the EP was evaluated. In experiment 2, a pool of EP and EJ sperm (n = 7) was coincubated with cumulus-oocyte complexes (COCs) for 0, 3, 6, 12 and 18 h, and the fertilization rate (FR) was evaluated. A third experiment was performed to test sperm treatments for IVP using the Percoll (P) or PureSperm (PS) gradients or a spTALP wash for sperm selection. Cleavage, blastocyst rate (BR) and embryo sex were evaluated. In experiment 4, embryos were produced using 6, 12, and 18 h of sperm-oocyte coincubation. The cleavage, BR, and total number and percentage of apoptotic cells were determined. Heparin affected EP viability, longevity and FR. After 6 h, 82% of the oocytes were fertilized in the EP+ group, a higher value (P<0.05) than that in the EJ (19%) and EP- (42%) groups. At 12 and 18 h, FR remained higher in the EP+ group, and a gradual increase in polyspermy was observed. The use of a P or PS gradient yielded a similar BR on D7 (54% and 52%), which was higher than the rate obtained using the washing method (37%). The embryos produced by EP and selected in a P or PS gradient resulted in a sex deviation in favor of male embryos (P>0.05). No differences (P>0.05) were observed among the groups that were coincubated for 6, 12 and 18 h with respect to embryo production, kinetics of development, total cell number and percentage of apoptotic cells. In conclusion, IVF time can be reduced to 6 h without affecting embryo production and quality. In addition, EP sperm selection can be performed by either a PS or P gradient.

Effect of length of time post-mortem on quality and freezing capacity of Cantabric chamois (Rupicapra pyrenaica parva) epididymal spermatozoa

Genome Resource Banks are keystones in the ex-situ conservation of wild species. Post-mortem (PM) collection of epididymal spermatozoa is an opportunistic and valuable source of germplasm, the time from the death of the animal limits its use. Seeking to improve germplasm preservation strategies for the chamois (Rupicapra sp.), the effect of PM time on epididymal sperm quality and freezability was studied using the Cantabrian chamois. Samples were classified according to PM collection time, up to 216 h (refrigerated), and cryopreserved (Tris-citric acid-fructose, 430 mOsm/kg, 15% egg yolk, 8% glycerol; freezing at -20 °C/min). Sperm quality was assessed after recovery and post-thawing (motility by CASA, HOS test, abnormal forms, cytoplasmic droplets, and viability and acrosomal damage by flow cytometry). The sperm mass pH and osmolality showed a positive correlation with time. Total sperm motility dropped after 2 days PM, with progressivity and sperm velocities remained similar up to 3 days PM. Sperm freezability was acceptable, with the post-thawing HOST, motility, progressivity, VAP, VCL, VSL and BCF negatively correlating with PM time. Overall, chamois epidydimal samples were not adequate for preservation after 6 days PM. Freezability capacity could make these spermatozoa suitable for specific ART even if kept refrigerated for several days PM.

Effect of Extender and Freezing Rate on Quality Parameters and In Vitro Fertilization Capacity of Alpaca Spermatozoa Recovered from Cauda Epididymis

In alpacas, improvement of reproductive efficiency of male camelids is limited by the small testicular size, low spermatozoa production, and low quality of semen. In this study we aim to evaluate the effect of two extenders and two freezing rates on post-thaw quality of sperm recovered from alpaca epididymis with two methods (flushing and mincing), and to evaluate the in vitro fertilization (IVF) capacity of frozen sperm selected with two different selection methods (washing and swim-up). Sperm samples were processed with Tris-egg yolk or Bioxcell^® extenders and frozen with slow freezing and fast freezing. The oocytes were coincubated with spermatozoa for 72 hours, and cleavage rates were recorded afterward. The results indicated that the recovery method did not influence sperm quality (∼70%). However, total sperm recovery was significantly lower for the flushing method than the mincing method. The sperm quality was influenced by the freezing extender (23.3% vs. 33.2%) and freezing rate (20.9% vs. 35.7%). When comparing different methods of sperm selection for IVF, no differences were observed on cleavage rate except for the fact that the concentration of sperm from swim-up method (20.6%) was significantly lower than the one obtained from the washing method (78.7%). The recovery technique of sperm does not affect sperm quality and the method of fast freezing was shown to be the most effective for cryopreservation of alpaca sperm.

Cryopreservation of collared peccary (Pecari tajacu L., 1758) epididymal sperm using extenders based on Tris and powdered coconut water (ACP®-116c)

The aim of this study was to establish a functional freezing–thawing protocol for epididymal sperm of collared peccaries (Pecari tajacu L., 1758) by comparing different extenders. The epididymal sperm from 12 sexually mature males was recovered by retrograde flushing using Tris-based or coconut water-based (ACP®-116c) extenders. After initial evaluation, samples were diluted and frozen with the same extenders to which 20% egg yolk and 6% glycerol were added. After 2 weeks, thawing was performed at 37°C/60 s and sperm motility, vigour, morphology, functional membrane integrity, sperm viability, sperm plasma membrane integrity, and a computer-assisted semen analysis (CASA) were assessed. In addition, to evaluate the survival of frozen–thawed sperm, a thermal resistance test (TRT) was executed. Samples preserved using Tris were in better condition compared with those preserved using ACP®, showing higher values for most assessments performed, including CASA and the TRT (P<0.05). After determining Tris to be the better of the two extenders, additional samples were thawed using different thawing rates (37°C/60 s, 55°C/7 s, 70°C/8 s). Sperm thawed at 37°C/60 s had the greatest preservation (P<0.05) of viability (54.1 ± 5.9%) and functional membrane integrity (43.2 ± 5.4%), and had higher values for various CASA parameters. In conclusion, we suggest the use of a Tris-based extender added to egg yolk and glycerol for the cryopreservation of epididymal sperm obtained from collared peccaries. In order to achieve better post-thawing sperm quality, we suggest that samples should be thawed at 37°C/60 s.

Viability of ovine spermatozoa collected from epididymides stored at 18°-25°C for 48 hours post mortem

ABSTRACT The objectives of this study were to verify the time during which viable ovine spermatozoa could be recovered from the cauda epididymis kept at ambient temperature (18-25°C). Sperm collected in an artificial vagina (AV) were used as control. Spermatozoa samples were collected with an AV and from epididymis at 0 (G0), 6 (G6), 12 (G12), 24 (G24), and 48 (G48) hours post mortem. Total motility (TM), progressive motility (PM), hypo-osmotic membrane integrity test (HOST) and morphological changes were assessed. TM decreased (P<0.05) from 24 hours post mortem (70.0±1.9%) compared to AV (86.4±1.0%). PM decreased (P<0.05) from 12 hours after death (31.3±4.0%) compared to AV group (73.2±1.4%). The percentage of viable cells in HOST decreased (P<0.05) in the G48 (60.0±8.9%). Spermatozoa recovery was lower (P<0.05) 48 hours after death (2064.2±230.7 x 106 spermatozoa) compared to G0(2623.6±288.4 x 106 spermatozoa). In conclusion, under the conditions of this study, it would be possible to use epididymal spermatozoa recovered up to 24 hours after death for artificial insemination or in vitro fertilization; however, fertility trials are necessary to prove this hypothesis.

Recovery of sperm after epididymal refrigeration from domestic cats using ACP-117c and Tris extenders

ABSTRACT We aimed to compare fresh sperm and sperm cooled to 4ºC that had been recovered from the epididymides of cats using powdered coconut water (ACP-117c) and Tris extenders. Sixty epididymides were divided into 6 groups: 10 fresh epididymides were recovered using Tris (T0h); 10 were kept at 4°C/2h and recovered using Tris (T2h); 10 were kept at 4°C/4h and recovered using Tris (T4h); 10 fresh were recovered using ACP-117c (A0h); 10 were kept at 4°C/2h and recovered using ACP-117c (A2h), and 10 were kept at 4°C/4h and recovered using ACP-117c (A4h). The testis-epididymis complexes (TEC) control were not cooled. The others were cooled at 4°C for 2 or 4h. The epididymis was separated and the sperm was recovered by the modified flotation method. Sperm kinetic parameters were evaluated by a computer-system analysis, and vigor, viability, concentration, membrane function and morphology of the sperm were assessed under a light microscope. The progressive motility with ACP-117c declined after 2h of cooling, but did not differ between fresh and 4h. The vigor and membrane function were higher in A4h than A0h. The vigor at T2h and T4h were decreased compared to T0h. T0h was higher than A0h for vigor and sperm membrane function. However, after 4h of cooling, ACP-117c maintained a higher percentage of living cells. Feline epididymal sperm quality can be maintained to the degree necessary for artificial breeding programs following cooling and ACP-117c may be successfully used to recover cat sperm that have been cooled for up to 4h.

In vitro and in vivo fertilization potential of cryopreserved spermatozoa from bull epididymides stored for up to 30 hours at ambient temperature (18 °C-20 °C)

The aims of this study were to compare the viability and in vivo and in vitro fertilization potential post-thaw sperm collected at different times postorchiectomy from bull epididymides (EP) at 18 °C to 20 °C, with those of semen collected by electroejaculation (EJ) from the same bulls. Semen samples were collected by EJ from 10 Zebu bulls and cryopreserved. A week later 20 epididymides from these bulls were obtained by orchiectomy and randomly divided into five groups (G) to be maintained at ambient temperature for 6, 12, 18, 24, and 30 hours before sperm recovery by retrograde flow. The sperm were cryopreserved, and post-thaw parameters were determined by both computer-assisted sperm analysis and morphologic analysis. In vitro fertilization of oocytes was performed to assess the cleavage rate, blastocyst rate, total number of cells, and hatching rate of embryos. The G30 sperm samples were also used for fixed time artificial insemination (FTAI) of Zebu heifers (n = 10). The results of post-thaw sperm viability showed that total and progressive motility and plasma membrane integrity were lower in sperm in which cryopreservation was delayed for 30 hours, showing a negative correlation of these parameters with delay before cryopreservation. In all groups, it was possible to obtain viable embryos, and embryos from G6 samples had more cells than the other groups. The greatest embryo production rates were observed in G6, G12 and G18 (27.2 to 32.2%) and it was significantly lower in G24 and G30 samples. For EJ, many individual variations were observed in embryo production potential between bulls. G30 samples, with only 5.2% of post-thaw progressive motility, were able to fertilize and produced a pregnancy. To the authors' knowledge, this is the first time in vitro embryos up to 8 days of development and a pregnancy after FTAI have been produced with sperm from bull epididymides that had been stored at 18 °C to 20 °C for up to 30 hours.

CRYOPRESERVATION OF ONAGER (EQUUS HEMIONUS ONAGER) EPIDIDYMAL SPERMATOZOA

Genetic diversity is a primary component of adaptive evolution, and its loss or reduction can decrease the long-term survival probability of populations. Utilization of cryopreserved semen may be considered a perfect tool to improve genetic diversity, reduce inbreeding, and avoid animal translocation for breeding. The present study aimed at finding a reliable epididymal sperm freezing protocol for the critically endangered onager (Equus hemionus onager). Six testicles from three animals were processed postmortem. The effects of two transportation temperatures (22°C and 4°C; testicles submerged in saline), two cryopreservation techniques (conventional liquid nitrogen vapor freezing in straws and directional freezing in 8-ml HollowTubes(TM)), and two postthaw incubation temperatures (22°C and 37°C; evaluated after 0.5, 1, 2, and 3 hr) were tested in a 2×2×2 experimental design. Sperm samples were evaluated for motility, viability, acrosome integrity, and sperm morphology. The resulting optimal freezing protocol includes transportation of testicles at 4°C, cryopreservation by directional freezing, and, if needed, postthaw incubation at 22°C. With this combination of transportation temperature and cryopreservation technique, the authors obtained the following postthaw values normalized to prefreezing values: 60.3±8.8% motility, 60.7±13.3% viability, 75.3±9.5% acrosome integrity, and 94.7±2.9% normal morphology (excluding defects due to the epididymal origin of the sperm). After incubation at 22°C, motility values for the above combination were 40±5.7%, 30.3±5.2%, 28.3±4.4%, and 16.7±4.4% for 0.5, 1, 2, and 3 hr, respectively. In conclusion, with this protocol, good quality semen can be stored for future use in artificial inseminations when and where needed.

Reduced glutathione addition improves both the kinematics and physiological quality of post-thawed red deer sperm

The potential protective effect of reduced glutathione (GSH) and trolox (TRX), an analogue of vitamin E, supplementation during in vitro culture (2h, 39°C) of electroejaculated frozen/thawed red deer sperm was investigated. Cryopreserved sperm were thawed and incubated with no additive (Control) and 1mM or 5mM of each antioxidant to find out whether these supplementations can maintain the sperm quality, considering the use of thawed samples for in vitro techniques such as in vitro fertilisation (IVF), sperm sex sorting or refreezing. The effect of GSH on sperm motility was positive compared to TRX which was negative (P<0.001). After 2h of incubation at 39°C, use of GSH improved motility while TRX supplementation reduced sperm motility compared with Control samples without antioxidant. Use of TRX at both concentrations (1 and 5mM; TRX1 and TRX5) resulted in lesser percentages of apoptotic sperm (12.4±1.1% and 11.7±0.9%) than GSH1, GSH5 (15.2±1% and 14.6±1.1%) and Control samples (16.9±1.2%) (P<0.001). Use of GSH at both concentrations (1 and 5mM) resulted in greater mitochondrial activity as compared with findings for the Control, TRX1 and TRX5 groups. Results of this study indicate that GSH is a suitable supplement for electroejaculated red deer sperm. It would be necessary to conduct fertility trials (in vivo and in vitro), to assess whether GSH supplementation of thawed red deer sperm could improve fertility rates.

Morphological defects of epididymal spermatozoa in male roe deer (Capreolus capreolus) during the reproductive season

The aim of this study was to analyse the morphology of the epididymal spermatozoa of male roe deer obtained postmortem at the beginning (May), peak (July/August) and the end (September) of the reproductive season. Spermatozoal abnormalities were divided into major (associated with impaired fertility) and minor (not associated with impaired fertility) defects. The highest percentage of abnormal spermatozoa was observed in May (17.78 ± 1.88%), with a much higher proportion of major (12.35 ± 1.11%) than minor defects (5.43 ± 1.59%) being observed. The percentage of abnormal spermatozoa was lowest during the peak of the reproductive season (4.97 ± 1.13%), with the proportion of major (2.68 ± 0.78%) and minor defects (2.28 ± 0.45%) being comparable during this period. The percentage of abnormal spermatozoa increased again in September (11.05 ± 1.60%), with the major defects (6.15 ± 1.04%) slightly surpassing the minor defects (4.90 ± 0.77%); however, total abnormalities still remained lower than those found in May. These differences were statistically significant, with the exception of the difference in minor defects between the pre-rut and post-rut periods. These results indicate that the best period to collect epididymal spermatozoa from roe deer postmortem is the peak of the reproductive season (July/August); however, they can also be recovered at the end of the reproductive season (September), as the percentage of major defects is relatively low at this time. This study provides the basis for further research to determine optimal methods for the storage and cryopreservation of epididymal spermatozoa in this species.

Fertility of undiluted ram epididymal spermatozoa stored for several days at 4°C

In vitro preservation of the male gamete is a challenge in the development of artificial insemination techniques for domestic animals. Specific strategies and diluents have been developed for the preservation of the fertilizing ability of the semen for each species. However, the epididymal medium has been demonstrated to be the best sperm environment to maintain sperm viability over several days and weeks for mammals. The aims of this study were to evaluate the motility and in vivo fertility of ram epididymal spermatozoa when the semen was stored for up to 4 days at 4°C undiluted in epididymal plasma. The study was undertaken with two ovine breeds (Ile de France and Corriedale). The motility of epididymal spermatozoa was better preserved in the undiluted epididymal fluid than when epididymal spermatozoa were diluted in classic ovine extender such as skim milk. During storage, the decrease in the percentage of motile sperm was lower if the epididymal spermatozoa were collected immediately after epididymal sampling than 24 h after castration or animal death. The fertility obtained after cryopreservation of the stored sperm and subsequent intrauterine insemination ranged from 55% to 24% following 24 to 96-h sperm storage. There was a linear regression relationship between fertility and the number of motile sperm inseminated for both breeds. These results show that it is possible to keep epididymal sperm motile and fertile for several days without dilution. Such a method of sperm preservation could be a final possibility for animals of high genetic value or for endangered species when the collection of semen before death of the animal is not possible.

Boar sperm cryosurvival is better after exposure to seminal plasma from selected fractions than to those from entire ejaculate

Boar bulk ejaculates are now being collected instead of usual sperm-rich fractions (SRF) for artificial insemination purpose. The present study evaluated the influence of holding boar sperm samples before freezing surrounded in their own seminal plasma (SP), from either fractions/portions or the entire ejaculate, on post-thawing sperm quality and functionality. Ejaculates collected as bulk (BE) or as separate (first 10 mL of SRF [P1] and rest of SRF [P2]) from 10 boars were held 24h at 15-17°C and then frozen. Some bulk ejaculate samples were frozen immediately after collections as Control. In addition, epididymal sperm samples from the same 10 boars were collected post-mortem and extended in SP from P1 (EP1), P2 (EP2) and post SRF (EP3), and also held 24h before freezing for a better understanding of the influence of SP on boar sperm cryopreservation. The sperm quality (motility, evaluated by CASA, and viability, evaluated by flow cytometry) and functionality (flow cytometry assessment of plasma membrane fluidity, mitochondrial membrane potential and intracellular generation of reactive oxygen species [ROS] in viable sperm) were evaluated at 30, 150 and 300 min post-thaw. Post-thawing sperm quality and functionality of P1 and P2 were similar but higher (p < 0.01) than BE samples. Control samples showed higher (p < 0.01) post-thaw sperm quality and functionality than BE samples. Post-thawing sperm quality and functionality of EP1 and EP2 were similar but higher (p < 0.05) than EP3. These results showed that boar sperm from BE are more cryosensitive than those from the SRF, particularly when held 24h before freezing, which would be attributable to the cryonegative effects exerted by the SP from post SRF.

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.

Dynamics of sperm subpopulations based on motility and plasma membrane status in thawed ram spermatozoa incubated under conditions that support in vitro capacitation and fertilisation

The present study evaluated modifications occurring in thawed ram spermatozoa during incubation in different media that supported in vitro capacitation and fertilisation, and examines how these changes relate to IVF. Thawed sperm samples were incubated under capacitating (Cap) and non-capacitating (non-Cap) conditions for 0, 1 and 2 h and used in an IVF test. During incubation, changes related to membrane status and the motility pattern of spermatozoa were assessed, the latter being used to characterise sperm subpopulations. A significantly greater increase (P ≤ 0.05) in the percentage of spermatozoa with higher membrane fluidity was observed in samples incubated with Cap medium from the beginning of incubation. In addition, changes over time in the distribution of the motile subpopulation were particularly evident when spermatozoa were incubated with Cap medium, with a noted increase in spermatozoa classified as ‘hyperactivated like’, with major changes occurring after 1 h incubation. Both characteristics (i.e. membrane fluidity and the percentage of the hyperactivated-like subpopulation) were significantly related with in vitro fertility, and only sperm samples incubated with the Cap medium were capable of fertilising oocytes. These results support the idea that changes in sperm membrane fluidity and motility pattern (i.e. an increase in hyperactivated spermatozoa) are needed for fertilisation to take place.

How developments in cryobiology, reproductive technologies and conservation genomics could shape gene banking strategies for (farm) animals

Many local breeds are currently at risk because of replacement by a limited number of specialized commercial breeds. Concurrently, for many breeds, allelic diversity within breeds declines because of inbreeding. Gene banking of germplasm may serve to secure the breeds and the alleles for any future use, for instance to recover a lost breed, to address new breeding goals, to support breeding schemes in small populations to minimize inbreeding, and for conservation genetics and genomics research. Developments in cryobiology and reproductive technology have generated several possibilities for preserving germplasm in farm animals. Furthermore, in some mammalian and bird species, gene banking of material is difficult or impossible, requiring development of new alternative methods or improvement of existing methods. Depending on the species, there are interesting possibilities or research developments in the use of epididymal spermatozoa, oocytes and embryos, ovarian and testicular tissue, primordial germ cells, and somatic cells for the conservation of genetic diversity in farm- and other animal species. Rapid developments in genomics research also provide new opportunities to optimize conservation and sampling strategies and to characterize genome-wide genetic variation. With regard to gene banks for farm animals, collaboration between European countries is being developed through a number of organizations, aimed at sharing knowledge and expertise between national programmes. It would be useful to explore further collaboration between countries, within the framework of a European gene banking strategy that should minimize costs of conservation and maximize opportunities for exploitation and sustainable use of genetic diversity.