Submission Number: AND-4-9-3

Abstract Number: 130

SPECIES-SPECIFIC SPERM-EGG INTERACTION AFFECTS THE UTILITY OF A HETEROLOGOUS BOVINE IN VITRO FERTILIZATION SYSTEM FOR EVALUATING ENDANGERED ANTELOPE SPERM.

Andy J Kouba* ¹, Angela D Rowson ¹, Mark D Atkinson ², A Rae Gandolf ² and Terri L Roth* ¹

Center for Research of Endangered Wildlife, Cincinnati Zoo and Botanical Garden, Cincinnati, OH 45220. ¹
The Wilds, Cumberland, OH 43732 USA. ²

Abstract:
The purpose of this study was to evaluate cryopreserved fringe-eared oryx (Oryx gazella) sperm function using a heterologous bovine in vitro fertilization (IVF) system previously developed to study scimitar-horned oryx (Oryx dammah) spermatozoa. Specific objectives were to: 1) characterize fringe-eared oryx sperm motility and acrosome integrity over time; 2) evaluate penetration, polyspermy and male pronuclear formation in cow oocytes after co-incubation with oryx sperm; 3) determine the cleavage rate of fringe-eared oryx-cow hybrid embryos; and 4) compare results to those from parallel studies with bull and scimitar-horned oryx spermatozoa. Cryopreserved spermatozoa were evaluated for motility, forward progression, and acrosomal status immediately post-thaw, after percoll-separation, and 1, 2, 3, and 8 h after culture in IVF medium (modified-Tyrode's solution). In vitro matured cow oocytes (n=924) were inseminated with bull, fringe-eared oryx, or scimitar-horned oryx spermatozoa (1x10⁶ motile sperm/ml). After an 8 h co-incubation, half the oocytes were fixed and examined for sperm penetration, polyspermy, and male pronuclear formation. The remaining oocytes were cultured in modified-KSOM and evaluated for cleavage after 48 h. Overall, there were no between-species differences in sperm motility and acrosome integrity (P>0.05). At the time of insemination, > 85% of spermatozoa were motile, however sperm motility decreased (P<0.05) over time for all species. Acrosome integrity remained constant (P>0.05) for both oryx species, but decreased (P<0.05) over time for the bull. Penetration, male pronuclear formation and embryo cleavage were high (>90%, >85%, and >70%, respectively) for oocytes inseminated with bull and scimitar-horned oryx spermatozoa and did not differ (P>0.05) between species. In contrast, very few oocytes (2.8%, 4/141) inseminated with fringe-eared oryx sperm were penetrated and just a single oocyte contained a male pronuclei. Cleavage was rare (8.0%, 16/200) in oocytes inseminated with fringe-eared oryx spermatozoa and did not differ (P>0.05) from that in parthenogenetic controls (4.2%, 3/72). These results indicate that species-specific differences in gamete function may exist even between very closely related non-domestic bovids. .

Keywords: In Vitro Fertilization and Antelope

This abstract is being presented at: 8:00 AM in session:
Fertilization