Snow Leopard ( Panthera uncia ) Spermatozoa Are Sensitive to Alkaline pH, But Motility In Vitro Is Not Influenced by Protein or Energy Supplements

Comparison of the Morphology and Developmental Potential of Oocytes Obtained from Prepubertal and Adult Domestic and Wild Cats

Simple Summary

This study was conducted with the aim of determining the morphological similarities and developmental potential of oocytes obtained from adult and prepubertal domestic cats (Felis catus) and wild cats. The results of our research showed that ovaries obtained from prepubertal felids may be a rich source of good quality oocytes that are competent for in vitro maturation and able to reach blastocyst stage after in vitro fertilization. The results are important in the context of the possibility of using oocytes from prepubertal felids threatened with extinction in conservation programs based on assisted reproductive techniques (ART).

Abstract

The aim of the study was to compare the morphology and developmental potential of oocytes obtained from adult and prepubertal domestic cats (Felis catus) and wild cats (Lynx lynx, Leptailurus serval, Felis manul, Panthera tigris altaica). The average number of oocytes obtained from an adult domestic cat was 23 ± 11, which was significantly lower than from kittens (43 ± 29). A similar number of oocytes was derived from adult Pallas’s cats (28 ± 8), and serval (30). The lowest number of oocytes was collected from the lynx (5 ± 3). No oocytes were obtained from newborn Amur tiger while in the case of older domestic and Pallas’s cat and lynx kittens (1–3 months) 43, 48 and 41 oocytes were collected, respectively. Significant differences (p < 0.001) were observed between the number of oocytes with dark cytoplasm from adult and prepubertal animals of all analyzed species. The diameter of oocytes from adult and prepubertal animals was similar in all species, and was on average 161 ± 4 µm for oocytes with dark cytoplasm and 150 ± 18 µm for oocytes with light cytoplasm. In all species, oocytes with light cytoplasm were significantly smaller (p < 0.05) than dark ones, and their population was more diverse. Results of in vitro maturation of the domestic and wild cat′s oocytes obtained from adult and prepubertal females were similar (47–52%). The cleavage rate after in vitro fertilization (IVF) was lower for prepubertal than adult domestic cats (42 vs. 51%; p < 0.05%). Moreover, we observed differences in the quantity (28 vs. 39%; p < 0.05) and quality of blastocysts and even greater problems with hatching blastocysts from prepubertal kittens (8 vs. 19%; p < 0.001). More blastomeres were detected in blastocysts of adult cats. They also demonstrated significantly higher number of inner cell mass (ICM) (p < 0.001) and higher number of trophoblast cells (TE) (p < 0.05).

Research in nondomestic species: experiences in reproductive physiology research for conservation of endangered felids

Tremendous strides have been made in recent years to broaden our understanding of reproductive processes in nondomestic felid species and further our capacity to use this basic knowledge to control and manipulate reproduction of endangered cats. Much of that progress has culminated from detailed scientific studies conducted in nontraditional laboratory settings, frequently at collaborating zoological parks but also under more primitive conditions, including in the field. A mobile laboratory approach is described, which incorporates a diverse array of disciplines and research techniques. This approach has been extremely useful, especially for conducting gamete characterization and function studies as well as reproductive surveys, and for facilitating the development of assisted reproductive technology. With continuing advances in assisted reproduction in rare felids, more procedures are being conducted primarily as service-related activities, targeted to increase effectiveness of species propagation and population management. It can be a challenge for both investigators and institutional animal care and use committees (IACUCs) to differentiate these service-based procedures from traditional research studies (that require IACUC oversight). For research with rare cat species, multi-institutional collaboration frequently is necessary to gain access to scientifically meaningful numbers of study subjects. Similarly, for service-based efforts, the ability to perform reproductive procedures across institutions under nonstandard laboratory conditions is critical to applying reproductive sciences for managing and preserving threatened cat populations. Reproductive sciences can most effectively assist population management programs (e.g., Species Survival Plans) in addressing conservation priorities if these research and service-related procedures can be conducted "on the road" at distant national and international locales. This mobile laboratory approach has applications beyond endangered species research, notably for other scientific fields (e.g., studies of hereditary disease in domestic cat models) in which bringing the laboratory to the subject is of value.

Scimitar-horned oryx (Oryx dammah) spermatozoa are functionally competent in a heterologous bovine in vitro fertilization system after cryopreservation on dry ice, in a dry shipper, or over liquid nitrogen vapor

A heterologous bovine in vitro fertilization (IVF) system was used to study the functional competence of scimitar-horned oryx spermatozoa after cryopreservation. Four sperm-freezing methods were compared after dilution of ejaculates from six oryx with an equine semen extender: 1) dry ice, 2) dry shipper one-step, 3) dry shipper two-step, and 4) liquid nitrogen vapor. Post-thaw sperm motility, longevity, and acrosomal status were assessed and zona pellucida penetration, fertilization, and embryo cleavage were evaluated after coincubation of thawed oryx spermatozoa with in vitro-matured domestic cow oocytes. Sperm motility index (SMI) decreased (p < 0.05) over a 6-h period, but a high percentage (>/= 65%) of spermatozoa contained intact acrosomes in all treatments. Despite differences in sperm motility among methods, oocyte penetration, fertilization, and embryo cleavage did not differ (p >/= 0.05). However, cleavage success was < 50% across all treatments. There were positive correlations (p < 0.05; r = 0.81-0.97) between sample SMI at 3 and 6 h and fertilization, penetration, and cleavage, but no correlations (p >/= 0.05) between SMI at 0 or 1 h and IVF success. This study demonstrates that compatible heterologous gamete interaction allows thorough assessment of post-thaw sperm function in an endangered antelope. Scimitar-horned oryx spermatozoa appear relatively tolerant of varied cryopreservation methods, and preserved samples exhibit adequate post-thaw function to warrant use for assisted reproduction.