Circannual variations in intraovarian oocyte but not epididymal sperm quality in the domestic Cat

Effect of season on the dynamics of cat sperm DNA fragmentation

BACKGROUND

Feline species undergo reproductive seasonality; thus, sperm characteristics, such as DNA integrity, can be affected by the photoperiod. This study was conducted to determine the effect of seasonal changes on sperm quality and on the dynamics of sperm DNA fragmentation. Epididymal spermatozoa were collected from 36 tomcats subjected to bilateral orchiectomy during breeding (BS) and non-breeding (NBS) seasons. Sperm samples were obtained by cutting the cauda epididymis and assessed for sperm motility, concentration, acrosome integrity, plasma membrane integrity and sperm morphology. Sperm DNA fragmentation was evaluated by the sperm chromatin dispersion test after 0, 6, and 24 h of incubation at 37 °C.

RESULTS

The total sperm motility and plasma membrane integrity values were greater during the BS, while the percentages of abnormal sperm and head defects were lesser (p < 0.05). No significant differences in DNA fragmentation were found between seasons after sperm collection. DNA damage was greater after 24 h of incubation at 37 °C in both seasons, although the percentage of spermatozoa with fragmented DNA was significantly lesser in the BS than in the NBS at 24 h (p < 0.05).

CONCLUSIONS

The study suggests seasonal changes in some of the quality parameters of cat sperm. DNA fragmentation dynamics were affected by the time of incubation and reproductive season; therefore, this technique might be used as an additional tool to test the potential fertility of semen samples used in feline-assisted reproduction.

The abundance and localization of claudin-1 and -5 in the adult tomcats (Felis catus) testis, tubules rectus, rete testis, efferent ductules, and epididymis

Tight junctions (TJ) are the anatomical component of blood-testis (BTB) and blood-epididymis (BEB) barriers and contain many proteins, including claudins. The presence of claudins in domestic cat testis and epididymis has not been previously described. This study aimed to determine whether claudin-1 and claudin-5 participate in the structure of BTB and BEB and whether their amounts differ between the testis and epididymal segments of adult cats, using Western blotting (WB) and immunohistochemistry. WB results demonstrated that claudin-1 was significantly lower in the testis than in all epididymal segments and higher in the corpus epididymis than in the cauda, while claudin-5 in the testis was significantly lower than in the caput and corpus. Claudin-1 was absent at the Sertoli-Sertoli junctions, while claudin-5 was detected at the level of the BTB during stages I and VIII. Both claudins were observed in the pachytene spermatocytes and the developing acrosome of the round and elongating spermatids. Claudin-5 was also detected in the cytoplasm of some spermatogonia, Sertoli cells, and late spermatid acrosome. In the epididymal segments, both claudins were localized to the area of the tight junctions and along the entire length of the lateral plasma membranes of adjacent principal cells and between principal and basal cells. These results may indicate that in the domestic cat, claudin-1 and -5 participate as both tight junction proteins and adhesion molecules in the BEB's structure, claudin 5 is a component of the BTB, and both proteins may be involved in postmeiotic germ cell development, especially acrosome development.

Proliferation and Apoptosis of Cat (Felis catus) Male Germ Cells during Breeding and Non-Breeding Seasons

Simple Summary

Spermatogenesis is a complex process through which male gametes, spermatozoa, are produced starting from stem germ cells called spermatogonia. The existing information on cat spermatogenesis is limited and somewhat contradictory. In fact, although this species is considered a long-day breeder with a reproduction period starting when the day length increases and ending in late autumn, spermatogenesis and sperm production occur throughout the year. In order to assess whether cat spermatogenesis is modulated according to a season pattern, we analyzed testes taken from feral cats orchiectomized during reproductive (February–July) and non-reproductive (November and December) periods. The results of the analyses carried out in the present study showed that spermatogonial proliferation was more intense during the reproductive period and germ cell death via apoptosis (a programmed form of cell death) increased during the non-reproductive period. Our results confirm the hypothesis that cat spermatogenesis is seasonally modulated through changes of germ cell proliferation and apoptosis, according to a common paradigm of seasonally breeding species.

Abstract

The domestic cat (Felis catus) is a seasonal-breeding species whose reproductive period starts when the day length increases. Since the existing information on cat spermatogenesis is limited and somewhat contradictory, in the present study, germ cell proliferation and apoptosis in feral adult tomcats orchiectomized during reproductive (reproductive group, RG; February–July) and non-reproductive (non-reproductive group, NRG; November and December) seasons were compared. Cross-sections taken from the middle third of the left testis were chemically fixed and embedded in paraffin wax. Histological sections were processed for the immunohistochemical detection of proliferating germ cells (PCNA) and for the identification of apoptotic cells (TUNEL method). The percentage of PCNA-positive spermatogonia was higher in the RG than in the NRG. On the contrary, germ cell apoptosis was higher in the NRG than in the RG. Our results confirm that cat spermatogenesis is modulated on a seasonal basis and suggests that spermatogenesis control involves changes in germ cell proliferation and apoptosis according to a common paradigm of seasonally breeding species.

Seasonal Effect on Developmental Competence, Oxidative Status and Tubulin Assessment of Prepubertal Ovine Oocyte

Simple Summary

Oocytes obtained from the ovaries of slaughtered prepubertal ewes can be incorporated into an in vitro embryo production system. The collection of this material is possible at two different times of the year, spring and autumn. The first period is linked to the natural reproductive cycle of the sheep. The second, on the other hand, is linked to the manipulation of the reproductive seasonality which allows the oestrus cycle to be controlled artificially. The analysis highlighted that the collection season influences oocytes quality from prepubertal donors in terms of improved energetic and oxidative status, microtubular organization, and developmental competence in oocytes recovered in spring. Data obtained underline that oocytes seem to be genetically and evolutionarily programmed to give their best in spring, this being the most favorable period for newborns.

Abstract

The reproductive seasonality of domestic animals is often manipulated in order to have more reproductive periods for commercial purposes related to the production of milk and meat. It is scientifically proven that such an alteration of the reproductive activity in sheep entails a deterioration in oocyte quality, leading to an inability to generate embryos. Since oocytes obtained from prepubertal ewes can be incorporated into an in vitro embryo production system and considering that their quality is crucial to the success of in vitro procedures, the aim of this work was to investigate the effect of seasons on the quality of prepubertal ovine oocytes collected in autumn and spring. Ovaries were collected from a local slaughterhouse from 30–40-day-old suckling lambs during both seasons. Following 24 h of in vitro maturation, oocytes developmental competence, reactive oxygen species (ROS) intracellular levels, and mitochondrial activity were evaluated, and a tubulin assessment was performed. The results on embryo production, as a percentage of first divisions and number of blastocysts obtained, were significantly higher in oocytes collected in the spring. Mitochondrial activity in oocytes was higher, and ROS production significantly lower, in spring than in autumn. Tubulin PTMs (tyrosinated and acetylated α-tubulin) showed a higher immunoreactivity in oocytes collected in spring compared with autumn sampling. Our data showed that seasons may affect the developmental competence, energetic status, and tubulin assessment of oocytes recovered from prepubertal ewes. Therefore, special care should be taken when choosing the period of the year for prepuberal ovine oocytes collection aimed at in vitro embryo reproduction programs.

Expression of Apoptosis-Related Genes in Cat Testicular Tissue in Relation to Sperm Morphology and Seasonality-A Preliminary Study

Simple Summary

Programmed cell death (apoptosis) is a crucial process in spermatogenesis, responsible for the elimination of abnormal sperm cells and for the reduction of testicular volume outside the breeding season. Poor sperm morphology (teratozoospermia) and lower semen quality out of season are commonly observed in domestic cats, but the exact reasons and mechanisms are not known. The aim of this study was to use gene expression analysis to identify which apoptotic processes and pathways are expressed in the phenomenon of teratozoospermia and seasonality in the domestic cat. The results showed a higher expression of two antiapoptotic genes and one proapoptotic gene during the non-reproductive season, with no differences noted between normozoospermic and teratozoospermic cats. We hypothesize that during the non-breeding season there is a potential detrimental factor which activates a cascade of caspases, against which germ cells mount a defense by producing anti-apoptotic proteins. Further identification of this factor may help in the amelioration of semen quality of cats and improve feline breeding.

Abstract

Apoptosis is a crucial process in spermatogenesis, responsible for the elimination of abnormal sperm cells and testicular regression out of breeding season. The aim of this study was to assess if the expression of apoptosis-related genes in testicular tissue of domestic cats differed: (1) between normozoospermic and teratozoospermic donors, and (2) between reproductive and non-reproductive season. The expression of genes: BCL2L1, BCL2, BAX, BAD, FAS, FASLG, and caspases (CASP3, CASP8, CASP9, and CASP10) was analyzed by qRT-PCR in testicular tissue samples. During non-reproductive season significantly higher expression of two anti-apoptotic genes (BCL2L1 and BCL2) was observed. Additionally, there was a significant higher expression of CASP10 in teratozoospermic cats during non-reproductive than during reproductive season. No differences were noted between normozoospermic and teratozoospermic groups. Upregulation of some genes during the non-reproductive season indicates engagement of apoptotic mechanisms in the seasonal changes of semen quality in cats, however further studies on protein levels and analysis of changes on distinct testicular germinal layers are required. At the same time, teratozoospermia in the general population of cats seems to be not connected with dysregulation of apoptosis in the testes.

Selection of Immature Cat Oocytes with Brilliant Cresyl Blue Stain Improves In Vitro Embryo Production during Non-Breeding Season

Simple Summary

The domestic cat is commonly used as a model for the development of assisted reproductive technologies, including in vitro embryo production (IVEP) in felid species. Seasonal reproduction is a feature of domestic cats as well as of several species of wild feline. Likewise, the number and the quality of blastocysts produced in in vitro systems is linked to season. Maintaining stable in vitro embryo production throughout the year is crucial not only for research purposes but also for programs aimed at protecting endangered felines. We assess whether using Brilliant Cresyl Blue (BCB) selection in addition to the classical morphological selection could improve the IVEP outcomes during non-breeding season. Blastocyst yield and quality of the embryos (hatching rate and blastocyst cell numbers) were higher after IVM/IVF in oocytes defined as BCB+ (colored cytoplasm) based on the BCB test than in oocytes only morphologically selected. Furthermore, no adverse effects on bioenergetic/oxidative status were observed in oocytes subjected to BCB staining. In conclusion, BCB test implementation in IVEP programs might ensure a steady output of domestic cat blastocysts throughout the year.

Abstract

In domestic cats, the maturation, fertilization, and development potential in vitro decreases during the non-breeding season. This study aims at evaluating the efficacy of Brilliant Cresyl Blue (BCB) staining in selecting developmentally competent oocytes to be used in in vitro embryo production (IVEP) programs in order to overcome the season variability in blastocyst yield. Cumulus-oocytes complexes (COCs) collected from antral follicles of domestic cat ovaries during the anestrus phase (July to November) were selected by BCB staining and classified as BCB+ (colored cytoplasm) and BCB− (colorless cytoplasm). COCs not exposed to BCB staining were used as control. Before and after in vitro maturation mitochondrial activity and reactive oxygen species (ROS) were measured. Following in vitro fertilization, blastocyst rate, hatching rate, and blastocyst cell numbers were recorded. The results show that BCB staining did not alter the mitochondrial function and ROS production in cat oocytes. BCB+ oocytes presented a higher (p < 0.05) blastocyst rate, hatching rate, and blastocyst cell number than BCB− and control oocytes. In conclusion, BCB staining does not affect the bioenergetic/oxidative status of the oocyte while being a useful tool for selecting good quality oocytes to increase IVEP in domestic cats during non-breeding season.

Cytological description of testicular cell populations in sexually mature cats with normal spermatogenesis

In cats, assessment of the testicular function is mainly based on sperm evaluation. Whatever the technique used, the volume of collected sperm is often small, which may lead to technical difficulties to achieve the semen evaluation in routine practice. Fine-needle aspiration (FNA) biopsy of the testicular parenchyma is one of the other methods used to assess testicular function. The aim of this study was to explore the relevance of FNA in the assessment of testicular cells in sexually mature cats. Eighteen cats over one year of age were recruited among animals presented for surgical neutering. Semen was collected by electroejaculation before it was evaluated. FNA biopsies of the testicles were taken using a 21-gauge needle. After castration, histological analysis of the testes was performed. Semen evaluation and histological analysis showed no anomalies, which confirmed normal spermatogenesis in all the cats and allowed a proper interpretation of the cytological findings. The cells identified through cytological examination were spermatogonia (1.99 ± 0.17%), primary spermatocytes (10.49 ± 0.74%), round spermatids (34.80 ± 1.57%), elongated spermatids (23.59 ± 2.02%), spermatozoa (21.56 ± 1.86%), Sertoli cells (7.53 ± 1.23%) and Leydig cells (0.04 ± 0.03%). However, spermatocytes II were not identified. This is due to the low proportions of these cells, related to their very short lifespan. Likewise, the very low number of Leydig cells observed is probably due to the damage caused during the aspiration stage. This study showed that fine-needle aspiration is an efficient method to describe cytologically normal testicular populations, a cornerstone for future research aimed to study abnormal spermatogenesis and to correlate it to cytological proportion of germ cells.

RFRP3 influences basal lamina degradation, cellular death, and progesterone secretion in cultured preantral ovarian follicles from the domestic cat

The hypothalamic neuropeptide RFRP3 can suppress hypothalamic GnRH neuron activation and inhibit gonadotropin release from the anterior pituitary. RFRP3 is also produced locally in the ovary and can inhibit steroidogenesis and follicle development in many vertebrates. However, almost nothing is known about the presence and regulatory action of RFRP3 in gonads of any carnivore species. Such knowledge is important for developing captive breeding programs for endangered carnivores and for inhibiting reproduction in feral species. Using the domestic cat as a model, our objectives were to (1) demonstrate the expression of feline RFRP3 (fRFRP3) and its receptor in the cat ovary and (2) assess the influence of fRFRP3 on ovarian follicle integrity, survival, and steroidogenesis in vitro. We first confirmed that fRFRP3 and its receptors (NPFFR1 and NPFFR2) were expressed in cat ovaries by sequencing PCR products from ovarian RNA. We then isolated and cultured preantral ovarian follicles in the presence of 10 or 1 µM fRFRP3 + FSH (1 µg/mL). We recorded the percentage of morphologically viable follicles (basal lamina integrity) over 8 days and calculated percentage survival of follicles on Day 8 (using fluorescent markers for cell survival and death). Last, we quantified progesterone accumulation in media. 10 µM fRFRP3 had no observable effect on viability, survival, or steroid production compared to follicles exposed to only FSH. However, 1 µM fRFRP3 decreased the percentage of morphologically viable follicles and the percentage of surviving follicles on Day 8. At the same time, 1 µM fRFRP3 increased the accumulation of progesterone in media. Our study shows, for the first time, direct action of RFRP3 on the follicle as a functional unit, and it is the first in a carnivore species. More broadly, our results support a conserved, inhibitory action of RFRP3 on ovarian follicle development and underscore the importance of comparative functional studies.

In Vitro Culture of Embryos from Domestic Cats

A variety of protocols are available for the production of feline blastocysts from oocytes that are matured and fertilized in vitro. However, most of these protocols utilize media that were developed for other cell types or the embryos of other species. The protocol outlined in this chapter is based on a series of studies that led to the development of feline optimized culture medium (FOCM), a feline-specific, sequential medium system. The initial embryo culture medium was subsequently modified for both IVM and IVF. Using a small number of stock solutions, a series of media can be easily prepared that allows for immature cat oocytes to be matured and fertilized in vitro, with the resulting embryos developing to the blastocyst stage without the use of serum.

The use of human and bovine commercial media for oocyte maturation and embryo development in the domestic cat (Felis catus)

The aim of this study was to examine the suitability of commercial media designed for humans and cattle for oocyte maturation and embryo culture in the domestic cat. In Exp. I, feline oocytes collected ex vivo were subjected to in vitro maturation in a laboratory-made culture medium (based on M199) or a commercial medium designed for cattle cells (BO-IVM^® ). In Exp. II, ICSI-derived feline embryos were cultured for 7 days in a commercial human (Continuous Single Culture^® ) or bovine (BO-EC^® ) cell medium. The rates of cleavage, morula and blastocyst formation were evaluated at 24 hr, 6 days and 7 days after ICSI, respectively, and compared between experimental groups. At the end of culture, embryos were assessed for viability and apoptotic changes. In Exp. I, no statistically significant difference in oocyte maturation outcome between laboratory-made (52.7%) and commercial media (58.9%) was observed. However, the use of a commercial medium prepared for use with bovine cells resulted in a significantly lower variance of the maturation rate. In Exp. II, no statistically significant differences between two commercial media were observed for cleavage (67.5% and 64.5%), morula (39.3% and 47.1%) and blastocyst rates (25.0% and 19.6%), as well as for the percentage of late apoptotic blastomeres. Morulae cultured in medium marketed for humans exhibited significantly more early apoptotic (43.2 ± 31.2% vs. 23.4 ± 23.2%) and necrotic (60.6 ± 47.6% vs. 29.4 ± 22.6%) blastomeres. In conclusion, both commercial media tested are suitable for in vitro oocyte maturation and embryo culture procedures in cats. It is remarkable that a culture medium designed for use in cattle for in vitro maturation of cat oocytes provides more reproducible results.

The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats

Toll-like receptors (TLRs) are important molecules, which provide protection against infections of the reproductive tract. This study demonstrates for the first time the expression and localization patterns of TLRs in the caput, corpus and cauda segments of the epididymal duct (ED) and the vas deferens (VD) of adult domestic cats using immunohistochemistry and western blotting. While immunoblot analyses revealed relatively similar protein levels for TLRs 2, 4, 5, and 9 in three segments of the ED, the protein levels of TLR2 and TLR4 in the VD were found to be significantly higher than those measured in the ED segments (P < 0.05). On the other hand, immunostaining showed that TLRs exhibited regional- and cell-specific localization patterns. TLR2 and TLR5 were immunolocalized to the nucleus and cytoplasm of the principal cells in all ducts. TLR4 was restricted to the stereocilia, and TLR9 was located in the cytoplasm of the principal cells. Narrow cells displayed positive immunoreactions for TLR4 and TLR5. The basal cells of the different ED segments were positive for all four TLRs. TLR2, TLR5 and TLR9 were detected in the cytoplasmic droplets of the spermatozoa. TLR4 and TLR9 were detected along the entire length of the sperm tail, whilst TLR2 and TLR5 were absent in the midpiece. TLR2 and TLR5 were also detected in the equatorial segment of the sperm head. These results suggest that TLR2, TLR4, TLR5 and TLR9 are important not only for the protection of the ED, VD and spermatozoa but also for the maturation and storage of spermatozoa in the ED and VD, respectively.

Brilliant cresyl blue staining allows the selection for developmentally competent immature feline oocytes

The outcome of in-vitro-maturation and in-vitro-fertilization of feline oocytes depends on the selection of high quality oocytes, and is often restricted to morphological criteria. The aim of this study was to test whether the Brilliant cresyl blue (BCB) staining is suitable for pre-selection of feline oocytes before in-vitro-maturation. Cumulus-oocytes-complexes (COC) were released from domestic cat ovaries obtained after ovariectomy and were subjected to BCB staining. BCB+ stained oocytes were characterized by a violet/pale blue staining of the ooplasma, BCB- oocytes remained unstained. Transmission electron microscopy indicated for a slightly advanced stage of BCB- oocytes within the maturation process. After 24 h in-vitro-maturation, almost 75% of BCB+ and 21.5% of BCB- oocytes were able to reach metaphase II. Also, after in-vitro-fertilization, significantly more oocytes developed to morulae (19.2%) if oocytes were preselected for BCB staining, although 8% of unstained COC still reached advanced embryo stages. Prolonged storage of ovaries before COC retrieval for 16-20 h at 4 °C was accompanied by reduced number of BCB+ oocytes (96 of 210, 45.7%) in comparison to freshly isolated COC (151 of 225, 67.1%), and impaired cleavage rate (19.8%) and morula rate (9.4%) of BCB+ oocytes but the rate of embryos which developed to advanced stages remained unchanged (∼50%). To conclude, BCB staining is a very useful tool to preselect immature COC of feline species ensuring higher developmental rates.

Effect of deslorelin acetate treatment in oocyte recovery and in vitro embryo production in domestic cats

Objectives The present study investigated the effect of contraceptive treatment with deslorelin acetate on in vitro embryo production and oocyte recovery in domestic queens. Methods Twenty-one mature domestic cats were used. Eleven queens (treated group) and one tom were kept in an experimental cattery, and 10 queens were privately owned (control group). When in interestrus or diestrus (day 0) a deslorelin acetate implant (Suprelorin, 4.7 mg/animal) was inserted into the subcutaneous tissue of the interscapular region in all queens in the treated group. After 6 months of treatment, all animals were ovariohysterectomized, and the ovaries were used for in vitro embryo production. Percentage of cleavage was determined 18 h after oocyte insemination and blastocyst formation was assessed on the eighth day of culture. The rate of cumulus-oocyte complexes (COCs) recovery was analyzed by an unpaired t-test. The cleavage and blastocyst rates were expressed as percentages and analyzed by Fisher's exact test. All analyses were performed using GraphPad Prism v5.0, with P <0.05 set as the level of significance. Results In the treated group, we recovered 8.3 ± 1.15 grade I COCs per queen; the cleavage rate was 60% and the blastocyst rate was 36%. In the control group, we recovered 18.4 ± 3.21 grade I COCs per queen; the cleavage rate was 55.97% and the blastocyst rate was 34%. Forty percent of treated females did not produce any blastocysts. In the treated group, we observed a significant decrease in COC recovery. Although there was no significant difference in cleavage and blastocyst rates between groups, 40% of treated females did not produce any blastocysts. Conclusions Recovery of grade I COCs is negatively affected by deslorelin treatment in domestic cats. Regarding embryo production, new studies are still necessary to evaluate the success of this technique owing to the individual effect caused by deslorelin acetate.

FSH stimulation of anestrous cats improves oocyte quality and development of parthenogenetic embryos

In the domestic cat, the efficiency of in vitro embryo production systems is negatively affected during the nonbreeding season. The objective of this research was to evaluate the effect of FSH stimulation in anestrous cats, on quality of cumulus-oocyte complexes (COCs) and in vitro developmental competence after parthenogenetic activation. To accomplish this purpose, anestrous cats were grouped into: (1) FSH treated (serial doses of 5 mg of porcine FSH each, every 24 hours, for 4 days) and (2) untreated control. The COCs were classified morphologically and a proportion of grade I and II COCs was used for expression analysis of FSHR, LHCGR, EGFR, PTGS2, EGR1, GDF9, and GATM by RT-qPCR. In addition, another proportion of grade I and II COCs was matured in vitro and used for parthenogenetic activation. After 8 days in culture, blastocyst and hatching blastocyst rates were assessed, and the expression of OCT4, SOX2, NANOG, CDX2, and GATA6 was evaluated. The COCs in the FSH group had an enhanced quality, a higher expression of LHCGR and a lower expression of GATM than did COCs from the control group (P < 0.05). Furthermore, embryos in the FSH group had increased blastocyst and hatching blastocyst rates, and those embryos had a higher expression of OCT4 and GATA than their counterparts from the control group (P < 0.05). In conclusion, ovarian stimulation of anestrous cats with FSH improved quality and increased the expression of LHCGR in COCs. The enhanced in vitro developmental competence, after parthenogenetic activation of oocytes from FSH-treated cats, coincided with an increased expression of OCT4 and GATA6 in blastocysts and hatching blastocysts.

Conservation of spermatogonial stem cell marker expression in undifferentiated felid spermatogonia

Spermatogonial stem cells (SSCs) are distinct in their ability to self-renew, transmit genetic information, and persist throughout the life of an individual. These characteristics make SSCs a useful tool for addressing diverse challenges such as efficient transgenic production in nonrodent, biomedical animal models, or preservation of the male genome for species in which survival of frozen-thawed sperm is low. A requisite first step to access this technology in felids is the establishment of molecular markers. This study was designed to evaluate, in the domestic cat (Felis catus), the expression both in situ and following enrichment in vitro of six genes (GFRA1, GPR125, ZBTB16, POU5F1, THY1, and UCHL1) that had been previously identified as SSC markers in other species. Antibodies for surface markers glial cell line-derived neurotrophic factor family receptor alpha 1, G protein-coupled receptor 125, and thymus cell antigen 1 could not be validated, whereas Western blot analysis of prepubertal, peripubertal, and adult cat testis confirmed protein expression for the intracellular markers ubiquitin carboxy-terminal hydrolase 1, zinc finger and BTB domain-containing protein 16, and POU domain, class 5, transcription factor 1. Colocalization of the markers by immunohistochemistry revealed that several cells within the subpopulation adjacent to the basement membrane of the seminiferous tubules and identified morphologically as spermatogonia, expressed all three intracellular markers. Studies performed on cheetah (Acinonyx jubatus) and Amur leopard (Panthera pardus orientalis) testis exhibited a conserved expression pattern in protein molecular weights, relative abundance, and localization of positive cells within the testis. The expression of the three intracellular SSC marker proteins in domestic and wild cat testes confirms conservation of these markers in felids. Enrichment of marker transcripts after differential plating was also observed. These markers will facilitate further studies in cell enrichment and IVC of felid SSCs enabling both production of transgenic domestic cats and preservation of the male genome from rare and endangered felids.

Region-specific localization of NOS isoforms and NADPH-diaphorase activity in the intratesticular and excurrent duct systems of adult domestic cats (Felis catus)

Nitric oxide (NO) is produced by nitric oxide synthases (NOSs) and plays an important role in all levels of reproduction from the brain to the reproductive organs. Recently, it has been discovered that all germ cells and Leydig cells in the cat testis exhibit stage-dependent nuclear and cytoplasmic endothelial (eNOS) and inducible (iNOS)-NOS immunoreactivity and cytoplasmic nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity. As a continuation of this finding, in this study, cellular localization of NADPH-d and immunolocalization and expression of all three NOS isoforms were investigated in the intratesticular (tubuli recti and rete testis), and excurrent ducts (efferent ductules, epididymal duct and vas deferens) of adult cats using histochemistry, immunohistochemistry and western blotting. NADPH-d activity was found in the midpiece of the spermatozoa tail and epithelial cells of all of ducts, except for nonciliated cells of the efferent ductules. Even though the immunoblotting results revealed similar levels of nNOS, eNOS and iNOS in the caput, corpus and cauda segments of epididymis and the vas deferens, immunostainings showed cell-specific localization in the efferent ductules and region- and cell-specific localization in the epididymal duct. All of three NOS isoforms were immunolocalized to the nuclear membrane and cytoplasm of the epithelial cells in all ducts, but were found in the tail and the cytoplasmic droplets of spermatozoa. These data suggest that NO/NOS activity might be of importance not only for the functions of the intratesticular and excurrent ducts but also for sperm maturation.

The influence of recombinant feline oviductin on different aspects of domestic cat (Felis catus) IVF and embryo quality

Oviductin is known to be a key player providing a convenient environment for the process of fertilization affecting this by direct interaction with oocytes and sperm. As in vitro embryo production in the context of assisted reproduction for endangered felids is still in the process of optimization, oviductin might be used to improve IVF results. Recombinant His-tagged feline oviductin was expressed by transformed Escherichia coli BL21DE3 cells. The protein was purified by immobilized metal ion affinity chromatography. The effect of the recombinant protein was characterized in three experiments: a hemizona assay for sperm binding analysis, the IVF outcome, and the relative mRNA expression levels in blastocysts after IVF. A significant higher number of bound sperm cells were found after incubation in oviductin. No significant effect on cleavage, morula, and blastocyst rates with or without oviductin incubation during IVF could be observed. However, the relative mRNA abundance of GJA1, a gene, whose expression level is known to be a marker of embryo quality, was significantly increased (P value less than 0.05) in blastocysts after oviductin treatment. In contrast to this, expression of OCT4, HSP70, DNMT1, DNMT3A, BAX, IGF1R, and GAPDH was not significantly affected. We assume that our recombinant oviductin in its current nonglycosylated form is able to enhance sperm binding. Despite of a missing significant effect on IVF outcome, embryo quality in terms of relative GJA1 expression is influenced positively. These promising results demonstrate the value of recombinant oviductin for the IVF in cats.

The seasonal and ovarian status effects on in vitro production of domestic cat embryos between Equator and Tropic of Capricorn

From the Tropic of Capricorn to Equator, the seasonality of domestic cat is known to be absent, i.e., these animals are considered non-seasonal breeders at these regions. We hypothesized that this particularity might have some influence on in vitro embryo production. The aim of this experiment was to determine the percentage of cleavage and morulae and blastocyst formation produced from oocytes recovered from queen ovaries of three distinct status - follicular, luteal or inactive - during two different reproductive seasons experienced by cats in southeast of Brazil (22°53'09" S and 48°26'42" W) - non breeding season (NBS), comprehending January to March; and breeding season (BS), August to October. Thirty queens were neutered. Ovaries were classified according to their status and were sliced in PBS for cumulus oocyte complex (COC) releasing. Grade I COC were washed three times in H-MEM supplemented with BSA, glutamine, sodium pyruvate, cysteine, streptomycin and penicillin. Oocytes were incubated in groups of 20-30 in 400µL of DMEM supplemented with FSH, LH, estradiol, IGF-I and basic fibroblast growth factor under mineral oil for 30 or 36 hours at 38°C in humidified environment of 5% de O2, 5% CO2 and 90% N2. COC were fertilized in Ham's F-10 medium supplemented with BSA, cysteine, pyruvate and streptomycin/penicillin (culture medium) with fresh semen selected through swim up technique. Eighteen hours later, the presumptive zygotes were denuded, the percentage of cleavage was determined and every 10 zygotes were transferred to 100mL drops of culture medium for culture during three days. After 72 hours of culture the percentage of morulae formation was evaluated and these structures were transferred to drops of the same culture medium. At the eighth day of culture blastocyst formation was analyzed. During NBS, from a total of 272 (inactive), 162 (luteal) and 134 (follicular) fertilized oocytes, the percentage of cleaved zygotes, morulae and blastocysts derived from inactive ovaries were 24.63, 16.54 and 8.09 respectively; for those derived from luteal ovaries, the percentage was 21.6, 12.96 and 8.64, and for those from follicular ovaries, they were 24.62, 16.41 and 8.21. Considering BS, from a total of 102 (inactive), 198 (luteal) and 86 (follicular) fertilized oocytes, the relative frequency (%) of cleaved zygotes, morulae and blastocysts derived from inactive ovaries were 64.7, 41.17 and 23.53 respectively; for those derived from luteal ovaries, the percentage was 64.14, 40.41 and 23.73, and for those from follicular ovaries, they were 63.95, 39.54 and 24.41. The results of this experiment demonstrate that no statistically significant difference (P<0.05) was verified in the frequency of cleaved embryos and morulae and blastocyst formation when comparing the three ovarian conditions in the same season. However the breeding season presented better results considering cleavage and morulae and blastocyst formation.

Cryoprotective effect of different glycerol concentrations on domestic cat spermatozoa

Cryopreservation of spermatozoa is a pivotal tool in assisted reproduction, and studies aiming to establish optimal freezing/thawing protocols are essential to enhance sperm survival. The objectives of the present study were to (1) compare the cryoprotective efficiency of three different glycerol concentrations (3%, 5%, and 7%) on the basis of post-thaw sperm quality and (2) investigate whether the incidence of morphologically abnormal sperm in fresh samples is related to cryodamage sensitivity. Semen was collected from six tomcats using an artificial vagina (total 18 ejaculates). Each ejaculate was diluted using Tris-egg yolk-based extender (TEY), evaluated, equally divided into three aliquots, and rediluted using TEY with and without glycerol to achieve final concentrations of 3%, 5%, and 7%. Samples were loaded into 0.25 mL straws, equilibrated for 60 minutes at 5 °C, frozen, and then thawed at 46 °C for 12 seconds. Fresh and frozen-thawed samples were evaluated for sperm motion parameters (computer-assisted sperm analysis), plasma membrane integrity (PMI; propidium iodide and carboxyfluorescein diacetate), and DNA integrity (acridine orange). Plasma and acrosomal membrane integrity were assessed by flow cytometry (propidium iodide and fluorescein isothiocyanate-conjugated pea (Pisum sativum) agglutinin) immediately after thawing. Sperm motion parameters were also evaluated at 30 and 60 minutes of postincubation. For all treatment groups, cryopreservation significantly impaired the PMI and sperm motion parameters, except for straightness and amplitude of lateral head displacement. DNA integrity showed a slight reduction (P < 0.05) when 3% glycerol was used. The percentage of total motility, progressive motility, and rapid spermatozoa were significantly lower immediately after thawing and up to 60 minutes of incubation for the 3% glycerol group when compared with 5% and 7%. No difference (P > 0.05) was found for PMI, acrosome integrity, and DNA integrity among post-thaw groups. However, higher (P < 0.05) incidence of viable cells with reacted acrosome and dead cells with intact acrosome were observed with 7% and 3% glycerol, respectively. Percentage of morphologically abnormal spermatozoa in fresh sample was positively correlated with PMI only in the 3% glycerol group and negatively correlated with sperm motility in the 5% and 7% groups. In conclusion, the final concentration of 5% glycerol offered better cryoprotective effect for ejaculated cat sperm, and the relationship found between prefreezing sperm morphology and post-thaw sperm quality showed to be dependent on final glycerol concentration.

Blastocyst rate of in vitro embryo production in sheep is affected by season

It has been reported that the number and quality of in vitro produced embryos is season related. This study was conducted to assess the effect of season on cleavage, blastocyst and lambing rates of in vitro produced ovine embryos during 3 years of collection data. Ovaries of Sarda sheep were collected from a slaughterhouse. In total, 5035 oocytes were recovered and matured in TCM-199 with 4 mg/ml bovine serum albumin (BSA), 100 μM cysteamine, 0.3 mM Na pyruvate, 0.1 UI/ml recombinant follicle-stimulating hormone (r-FSH), 0.1 UI/ml recombinant luteinising hormone (r-LH), and 1 μg/ml estradiol-17β. Matured oocytes were fertilized with fresh semen in synthetic oviductal fluid (SOF) with 20% heat inactivated estrous sheep serum. The presumptive zygotes were cultured for 6-7 days (blastocyst stage) in SOF medium supplemented with 1% Basel Medium Eagle (BME), 1% Minimum Essential Medium, 1 mM glutamine and 8 mg/ml fatty acid-free BSA. The embryos produced were vitrified and a total of 165 blastocysts (80 from the breeding season and 85 from the anoestrous season) were transferred in pairs into recipient ewes during the reproductive period. There were no significant differences in cleavage rates between seasons in any of the 3 years examined (84% versus 83%, 81% versus 80% and 80% versus 79%, respectively). The blastocyst rate varied significantly between seasons in 2005 and 2007 (P < 0.05), and in 2006 (P < 0.001). There were no differences in pregnancy and lambing rates between embryos during anoestrous versus during the breeding season. In conclusion, only the blastocyst rate appeared to have been affected by season, possibly due to variation in the number of developmentally competent oocytes.

Analysis of Sertoli cell efficiency allows the differentiation between two fundamentally different forms of feline teratospermia

Teratospermia is a common phenomenon within felid species and has been attributed to reduction in genetic diversity. Testes from teratospermic domestic cats show enhanced spermatogenesis accompanied by remarkably reduced germ cell apoptosis. In the present study we investigated whether free-range teratospermic tom cats exhibit a similar testicular phenotype as proven permanently teratospermic males. Randomly collected teratospermic cats were compared with normal (normospermic; >60% morphologically normal sperm per ejaculate) and a well-characterized population of permanently teratospermic domestic cats, with respect to their spermatogenic potential. Histomorphologic assessment of testes from randomly collected teratospermic cats revealed no differences compared with normospermic donors. These two groups, however, were both different from permanently teratospermic cats, which exhibit fewer Sertoli cells and increased numbers of round spermatids per tubule cross-section resulting in a remarkably increased Sertoli cell efficiency (ratio of round spermatids to Sertoli cells). In conclusion, we can distinguish at least two fundamentally different forms of feline teratospermia. One subtype, found in most of the randomly collected tom cats, but not associated with altered quantitative spermatogenic parameters. Another subtype, found in all permanently teratospermic felids, is manifested by an impairment of Sertoli cell efficiency. We suggest that spermatogenic output should be analyzed before using random source domestic cats to study the phenomenon of teratospermia.

Influence of culture medium composition on relative mRNA abundances in domestic cat embryos

Different culture conditions have been used to produce domestic cat embryos. As part of the in vitro procedures, the medium composition significantly affects the quality of the embryo development also. Quality assessments based on cleavage kinetics and blastomere symmetry are useful, but embryos also can differ in their relative gene expression patterns despite similar morphological characteristics. The aim of this study was to compare cat embryos produced with two different in vitro culture systems routinely used in two different laboratories [Smithsonian Conservation Biology Institute, Washington D.C., USA (SCBI) and Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany (IZW)]. Specifically, relative mRNA expression patterns of critical genes for pre-implantation embryo development were assessed in both conditions. Embryos were produced in parallel in both culture systems by IVF using frozen-thawed ejaculated semen in the United States and fresh epididymal sperm in Germany. Success of embryo development in vitro was recorded as well as relative mRNA abundances [DNA methyltransferases 1 and 3A (DNMT1, DNMT3A), gap junction protein alpha 1 (GJA1), octamer-binding transcription factor 4 [OCT4], insulin-like growth factors 1 and 2 receptors (IGF1R, IGF2R), beta-actin (ACTB)] in pools of days 4-5 morulae by semi-quantitative RT-PCR assay. Percentages of cleaved embryos were similar (p > 0.05) between both culture systems, regardless of the location. OCT4 mRNA abundance was higher (p < 0.05) in embryos derived in the SCBI culture system compared with those from the IZW system when epididymal sperm was used for IVF. No clear correlation between the expression pattern and the culture system could be found for all other genes. It is suggested that OCT4 expression might be affected by the media composition in some conditions and can be the indicator of a better embryo quality.

Absence of seasonal changes in FSHR gene expression in the cat cumulus-oocyte complex in vivo and in vitro

Domestic cat oocytes are seasonally sensitive to FSH. Compared with those collected during the breeding season, oocytes from the nonbreeding (NB) season require more FSH during in vitro maturation to achieve comparable developmental competence. This study tested the hypothesis that this seasonal variation was due to altered expression of FSH receptors (FSHR) and/or FSH-induced genes. Relative expression levels of FSHR mRNA and FSH-enhanced gene estrogen receptor β (ESR2) were measured by qPCR in whole ovaries and immature cumulus-oocyte complexes (COCs) isolated from cat ovaries during the natural breeding vs NB seasons. Expression levels of FSH-induced genes prostaglandin-endoperoxide synthase 2 (PTGS2), early growth response protein-1 (EGR1), and epidermal growth factor receptor (EGFR) were examined in mature COCs from both seasons that were a) recovered in vivo or b) matured in vitro with conventional (1 μg/ml) or high (10 μg/ml) FSH concentrations. Overall, FSHR mRNA levels were lower in whole ovaries during the NB compared with breeding season but were similar in immature COCs, whereas ESR2 levels did not differ in either group between intervals. We observed changes in PTGS2, EGR1, and EGFR mRNA expression patterns across maturation in COCs within but not between the two seasons. The lack of seasonal differentiation in FSH-related genes was not consistent with the decreased developmental capacity of oocytes fertilized during the NB season. These findings reveal that the seasonal decrease in cat oocyte sensitivity to FSH occurs both in vivo and in vitro. Furthermore, this decline is unrelated to changes in expression of FSHR mRNA or mRNA of FSH-induced genes in COCs from antral follicles.

Prediction of maturational competence of feline oocytes using supravital staining of cumulus cells by propidium iodide

We examined the relationship between integrity of cumulus cells and nuclear maturation rate after in vitro culture to determine a non-invasive prediction of the maturational competence of feline oocytes. Feline cumulus-oocyte complexes (COCs) were collected from either small (400-800 μm) or large (≥800 μm) follicles. Immediately after collection, cumulus cells were evaluated morphologically (thickness of cumulus cell layers) and stained with propidium iodide (PI), which penetrates only non-viable cells. Cumulus cells without PI staining were judged as having good membrane integrity. After evaluation, COCs were cultured for 30 h and their nuclear maturation rate was determined. The nuclear maturation rate of oocytes derived from large follicles (89.8%) was higher (p < 0.05) than that from small follicles (60.8%). There was no difference in the maturation rate of oocytes from follicles with the same size regardless of cumulus morphology. In contrast, oocytes that had cumulus cells with good membrane integrity showed a higher maturation rate (93.8%) than oocytes with poor cumulus integrity (76.9%) in large follicles (p < 0.05). We conclude that evaluation of membrane integrity of cumulus cells by propidium iodide staining can be used to predict the maturational competence of oocytes.

Effects of radiographic contrast media on domestic cat epididymidal sperm

Laparoscopic artificial insemination has an important role in felid conservation but it is costly and includes surgical risk. Therefore, radiographic contrast medium combined with non-surgical transcervical AI to verify intrauterine gamete placement could be a viable alternative. Gamete-rescued fresh and frozen-thawed sperm were extended with one of two commercial contrast media (nonionic and ionic), with osmolarity adjusted to 320-330 mOsm, or feline optimized culture medium (control). Percent motility, forward progression status, and acrosomal integrity were recorded every 30 min for 4 h. Sperm penetration abilities were assessed by coincubating treated sperm with conspecific in vitro matured oocytes for 18 to 20 h, and presumptive zygotes and embryos were fixed and stained to determine sperm penetration and fertilization rate. There was reduced motility and acrosomal integrity in frozen-thawed versus fresh sperm (P < 0.05). Neither radiographic contrast medium induced adverse effects on fresh sperm motility relative to control medium (P > 0.05), but motility of frozen-thawed sperm decreased when treated with nonionic radiographic contrast medium compared to control medium (P < 0.05). There were no differences in acrosomal integrity between radiographic contrast and control media in fresh (P > 0.05) or frozen sperm (P > 0.05). Neither radiographic contrast media decreased the numbers of morphologically normal sperm (P > 0.05) or reduced the ability of domestic cat sperm to penetrate (P > 0.05) or fertilize (P > 0.05) conspecific oocytes. Ionic radiographic contrast medium can be added to fresh or frozen-thawed domestic cat sperm with no adverse effect on motility, morphology, acrosomal integrity or oocyte penetration rates, and thus may be used to facilitate further development of transcervical AI procedures.

The effect of ovarian status and follicular diameter on maturational ability of domestic cat oocytes

The objective of this study was to clarify the effect of ovarian status and follicular size on morphological normality and maturational ability of cat oocytes. Ovarian status was classified into inactive, follicular, luteal and prepubertal, and follicles were classified into three groups according to their diameter (400-800, 800-1200 and 1200-2000 µm). In each ovarian status, the number of follicles decreased but the percentage of morphologically normal oocytes increased with the growth of follicles (p<0.05). Only a single follicle that was 1200-2000 µm in diameter was observed in two of the five prepubertal cats. In follicles that were 800-1200 µm in diameter, the percentage of normal oocytes and maturation rate were higher in prepubertal cats than in mature cats (p<0.05). Oocyte diameter tended to increase with the growth of follicles. After oocytes were cultured individually in droplets of maturation medium, the oocyte maturation rate increased with the growth of follicles in each ovarian status (p<0.05). In conclusion, oocytes collected from larger follicles possess higher maturational ability in vitro in sexually mature cats. In prepubertal cats, a higher maturation rate can be obtained from oocytes derived from small follicles compared with in mature cats.

Patterns of testicular activity in captive and wild Canada lynx (Lynx canadensis)

Canada lynx are listed as a threatened species in the contiguous US. Understanding the reproductive characteristics (i.e., mating system, behavior, physiology) of a species is useful for ensuring effective in situ and ex situ management plans. The goal of this study was to describe patterns of androgen expression in both captive and wild male Canada lynx using fecal hormone metabolite analysis. Among captive lynx, juvenile and castrated males had lower concentrations of fecal androgens (fA) than intact males, thereby demonstrating that the assay detects biologically meaningful differences in testicular activity. We found that captive males in general had much higher fA levels than wild males. All males showed strong seasonal variation in fA concentrations, with significantly higher levels being expressed during the breeding season (February and March) than during the non-breeding season. Among captive males, variation in seasonal fA levels did not correlate with latitude. Finally, males housed with intact cage-mates (either male or female) had significantly higher fA levels than males housed alone or with a neutered cage-mate.

Embryonic gene activation in in vitro produced embryos of the domestic cat (Felis catus)

Accurate embryonic gene activation (EGA) is essential for the embryo's developmental potency and reflects the quality ofin vitroproduced embryos. To describe the dynamic and temporal patterns of EGA in the cat, the mRNA expression of developmentally important genes (DNA methyltransferases 1 and 3A,DNMT1andDNMT3A; gap junction protein α 1,GJA1; transcription factor octamer 4,POU5F1(OCT4); insulin-like growth factor (IGF) 1 and 2 receptors,IGF1RandIGF2R) was examined by RT-PCR techniques in preimplantation embryos obtained afterin vitromaturation and IVF. Furthermore, influences of ICSI and sperm cryopreservation on the relative mRNA abundance in 4–5-days-old morulae were analyzed. Total RNA was obtained from immature and matured oocytes, 2-cell embryos, 4-cell embryos, and 8–16-cell embryos, morulae, and blastocysts. RNA was transcribed into single-stranded cDNA by reverse transcriptase. After amplification, a nonfelid standard RNA was used for semiquantitative analysis. Our results showed an increase in transcript abundance from the matured oocyte to the 2-cell embryo for all examined genes except forIGF2R, indicating that,in vitro, the embryonic genome is activated shortly after fertilization. However, the activation pattern varied markedly between the different genes. We also found different patterns of mRNA expression for the examined genes in morulae produced either by IVF or ICSI, and using fresh or cryopreserved sperm. Owing to high variations within the single groups of compared morulae, we were able to observe only a tendency toward higher relative mRNA expression in embryos derived by IVF with fresh sperm in comparison to all other groups.

Progestin exposure before gonadotropin stimulation improves embryo development after in vitro fertilization in the domestic cat

This study investigated the influence of progestin priming and ovarian quiescence on response to exogenous gonadotropin stimulation in the cat. Because a subpopulation of cats routinely ovulated spontaneously, there also was the opportunity to examine the ovary's reaction to the added impact of endogenously secreted progestagen. Queens were given 1) equine chorionic gonadotropin (eCG) plus human chorionic gonadotropin (hCG) only (control; n = 9 cats), 2) GnRH antagonist (antide) injections followed by eCG and hCG (n = 9), and 3) a progestin implant (levonorgestrel) followed by eCG and hCG (n = 9). Laparoscopy was used to assess ovarian activity and aspirate follicular oocytes that were graded on the basis of morphology. In five cats per treatment, half of the high-quality oocytes were assessed for glucose, pyruvate, and lactate metabolism as well as nuclear maturation. Remaining oocytes were inseminated in vitro, cultured, and examined at 72 h after insemination for cleavage. In the remaining four cats per treatment, all oocytes were inseminated in vitro and assessed at 72, 120, and 168 h after insemination for embryo developmental stage. Cats pretreated with progestin had more follicles and produced more embryos per donor (including at the combined morula/blastocyst stage) than controls or females treated with GnRH antagonist (P < 0.05). There were no differences among groups (P > 0.05) in oocyte carbohydrate metabolism, nuclear maturation metrics, or fertilization success, although there was a tendency toward improvements in all three (P < 0.2) in progestin-treated females. Interestingly, cats that spontaneously ovulated within 60 days of treatment onset also produced more embryos per cat than induced-ovulation counterparts (P < 0.05). Results indicate that prior exposure to exogenous progestin (via implant) or endogenous progestagen (via spontaneous ovulation) improves ovarian responsiveness to gonadotropins in the cat through a mechanism that is independent of the induction of ovarian quiescence.

Plasma hormone levels and semen quality in male cats during non-breeding and breeding seasons

Female cats are known to be seasonal breeders and male cats annual breeders. Despite this, there are limited data on the influence of breeding season (BS) on hormone concentration and semen quality in the male cat. This study compared plasma concentrations of LH and testosterone (T), and semen quality during the non-breeding season (NBS) and BS in five male cats subject to natural hours of daylight but a constant environmental temperature. Plasma LH and T concentrations were higher during the BS in 2/35 and 3/5 cats, respectively, although when comparing both hormones combined, values were higher during the BS than the NBS in all cats (p < 0.01). There were no significant differences in the percentage of abnormal sperm between the cats. Overall, semen quality was superior during the BS with larger semen volume in 2/5, sperm motility in 2/5 and sperm viability in 3/5 cats. Although there was a clear seasonal effect on hormone secretion and semen quality, during the NBS all cats were likely to have been fertile.

Seasonal changes in testicular cell morphology in domestic male cats (Felis catus)

The aim of this study was to asses the variation in the morphology of the seminal epithelium in relation to natural photoperiod in male cats. Tom cats (n = 240) were castrated every other week throughout the year. Each testis was fixed in Bouin's solution and cut into sections. The percentage of tubules with round spermatids (RS), elongated spermatids (ES), tailed spermatids (TS), mature spermatids (MS) and the number of Sertoli cells (SC) and Leydig cells (LC) were recorded in each sample. Testicles from males during short days (SHD) had a higher percentage of tubules with RS and ES compared to testicles from males during long days (LHD, 31.3 +/- 0.6 vs 2.1 +/- 0.6%, p < 0.001; 30.9 +/- 0.7 vs 11.0 +/- 0.7%, p < 0.001). Conversely, testicles from males during SHD had a lower percentage of tubules with TS and MS compared to testicles from males during LHD (24.5 +/- 0.8 vs 29.7 +/- 0.8%, p < 0.01; 13.1 +/- 1.2 vs 57.0 +/- 1.2%, p < 0.01). Furthermore, testicles from males during SHD had a higher number of SC and lower number of LC compared to testicles from males during LHD (11.4 +/- 0.1 vs 8.0 +/- 0.1%, p < 0.01; 19.2 +/- 1.0 vs 38.0 +/- 1.0%, p < 0.01). In conclusion, there are seasonal changes in testis cell morphology in the tom which may be related to seasonal sperm production.

Cryopreservation of feline epididymal spermatozoa from dead and alive animals and its use in assisted reproduction

Cryopreservation of gametes is an important tool in assisted reproduction programmes; long-term storage of oocytes or spermatozoa is necessary when in vitro fertilization (IVF) or artificial insemination is to be performed at a future date. Cryopreservation of epididymal spermatozoa offers a potential tool for rescuing genetic material from males of endangered populations. The objectives of this work were to: (1) examine sperm motility, viability, abnormality and acrosome integrity of frozen–thawed domestic cat epididymal spermatozoa; and (2) evaluate the same cryopreservation method on wild feline spermatozoa, needed to preserve their genetic resources. Epididymides were collected from 20 domestic cats during routine neutering procedure and from two wild felines at autopsy. The sperm samples, diluted with 4% glycerol/Tris/egg yolk, were loaded into 0.25 ml mini-straws, exposed to nitrogen vapour and stored in liquid nitrogen. After 4 weeks, samples were thawed and re-evaluated. The quality of each fresh and frozen–thawed sperm sample was tested by determining the motility (54.7 ± 11.3% and 32 ± 13.1% respectively for cat spermatozoa; 38.3 ± 18.7% and 21.5 ± 16.8% respectively for tiger spermatozoa), viability (74.3 ± 8.6% and 45.2 ± 9.4% respectively for cat spermatozoa; 42.4 ± 14.5% and 33.5 ± 12.9% respectively for wild felid spermatozoa), morphology and acrosomal status. The present study showed that feline epididymal spermatozoa can be frozen in egg-yolk extender with 4.0% glycerol in 0.25 ml straws. The procedure used in the present study for epididymal cat sperm cryopreservation may be applied to bank the genetic resources of wild felid species.

Impact of anisosmotic conditions on structural and functional integrity of cumulus-oocyte complexes at the germinal vesicle stage in the domestic cat

During cryopreservation, the immature oocyte is subjected to anisosmotic conditions potentially impairing subsequent nuclear and cytoplasmic maturation in vitro. In preparation for cryopreservation protocols and to characterize osmotic tolerance, cat cumulus-oocyte complexes (COC) at the germinal vesicle (GV) stage were exposed for 15 min to sucrose solutions ranging from 100 to 2,000 mOsm and then examined for structural integrity and developmental competence in vitro. Osmolarities > or =200 and < or =750 mOsm had no effect on incidence of oocyte nuclear maturation, fertilization success, and blastocyst formation compared to control COC (exposed to 290 mOsm). This relatively high osmotic tolerance of the immature cat oocyte appeared to arise from a remarkable stability of the GV chromatin structure as well as plasticity in mitochondrial distribution, membrane integrity, and ability to maintain cumulus-oocyte communications. Osmolarities <200 mOsm only damaged cumulus cell membrane integrity, which contributed to poor nuclear maturation but ultimately had no adverse effect on blastocyst formation in vitro. Osmolarities >750 mOsm compromised nuclear maturation and blastocyst formation in vitro via disruption of cumulus-oocyte communications, an effect that could be mitigated through 1,500 mOsm by adding cytochalasin B to the hyperosmotic solutions. These results (1) demonstrate, for the first time, the expansive osmotic tolerance of the immature cat oocyte, (2) characterize the fundamental role of cumulus-oocyte communications when tolerance limits are exceeded, and (3) reveal an interesting hyperosmotic tolerance of the immature oocyte that can be increased two-fold by supplementation with cytochalasin B.

Effects of the reproductive status on morphological oocyte quality and developmental competence of oocytes after in vitro fertilization and somatic cell nuclear transfer in cat

This study was conducted to examine the effects of the reproductive cycle of donor cat on the quality of oocytes at recovery and developmental competence of oocytes after in vitro fertilization (IVF) and somatic cell nuclear transfer (NT). Based on the presence or absence of follicles and corpora lutea, the ovarian pairs collected were classified into inactive, follicular or luteal stages. After collection of oocytes, the oocytes were classified into four grades according to the morphological condition of oocyte cytoplasm and cumulus cells. A total of 16 558 oocytes were obtained from 198 ovarian pairs. The total mean numbers of oocytes and the mean numbers of oocytes with high quality (grade I) were significantly higher in ovarian pairs at the inactive stage (111.1 and 19.0 oocytes, respectively) than in ovarian pairs at the follicular stage (67.1 and 11.4 oocytes, respectively). A significant difference in the proportions of oocytes with grade I out of the total examined oocytes was observed between the follicular and luteal stages of ovaries (14.9% vs 20.2%, p < 0.05). The proportions of IVF embryos cleaved and developed to blastocysts significantly decreased with decreased quality of oocytes at recovery, irrespective of the reproductive status of ovaries. Moreover, there were no significant differences in the proportions of cleavage and development to the blastocyst stage of IVF and NT embryos among three oestrous stages of ovaries. These results indicate that the reproductive cycle stage of donor cat ovaries has no apparent effects on the in vitro development of oocytes after IVF and NT, but the quality of oocytes at recovery influences the development of IVF embryos.

Apoptotic changes in the epithelium germinativum of the cat (Felis catus s. domestica, L. 1758) at different ages and breeding seasons

Apoptosis (programmed cell death) could be considered as a physiological process that takes part in a healthy organism, which helps to maintain organism homeostasis. The visible deterioration of semen quality and the number of germ cells is accompanied by a seasonal decrease of the reproductive activity in some species. This post-effect cascade is caused by apoptosis, which is the primary mechanism responsible for the elimination of germ cells during spermatogenesis. The aim of our study was to assess apoptotic changes in the epithelium germinativum in cat testes at different ages. One hundred and two pairs of testes were obtained from domestic cats aged between 4 months and 10 years. The paraffin-embedded tissue sections were labelled using the Oncogene and Calbiochem Research Products DNA Fragmentation Detection Kit (Cat# QIA21; Darmstadt, Germany), which allows the recognition of apoptotic nuclei in tissue sections with Fragment End Labelling (FragEL) of DNA. The activity of apoptotic processes in cat testes collected from the spring-summer period compared with the autumn-winter season revealed that, 59.42% and 51.51%, respectively, males testes were characterized by insignificant changes. The obtained data revealed a distinctive apoptotic changes in the young animal testes before spermatogenesis onset. An intensification of programmed death cells in the epithelium germinativum in the elder cats (between 3-6 and 6-10 years) was not observed. Apoptotic changes slightly intensified in cats aged between 12 and 36 months.