The proposed research is designed to investigate the factors that regulate the longevity of spermatozoa during their prolonged retention in the male epididymal duct system and storage in the female reproductive tract. During this period (6-9 months) they remain viable, fertile and morphologically unaltered. The major objectives are to determine whether longevity is an inherent property of bat spermatozoa or, conferred by features of the reproductive tract environment. We wish to further characterize the uterine environment by determining if glucose is present (we have already reported on fructose) and by further evaluating the role of carnitine (we have demonstrated its cyclic presence) and determine if these substances and zinc play a role in sperm survival. The ultimate control of sperm longevity may be in the deferment of capacitation; we will evaluate steroid male and female hormones amd also ambient and body temperature, factors preliminary experiments have demonstrated may be responsible for delaying capacitation and the normal onset of postcoital degenerative events (acrosome reaction, phagocytosis). Our approach will involve long-term and short-term experiments. Long term experiments will be designed to further characterize the uterine environment and its influence on stored sperm will be carried out over two reproductive cycles and thus will take two years to complete. Short-term experiments investigating the roles of steroids, ambient temperature, extracellular glucose, zinc and carnitine on viability, mobility, metabolism and capacitation of bat spermatozoa are designed to give quick yes-no answers. These studies are expected to yield valuable information relative to the control of spermatozoan capacitation and provide a basis to elucidate the mechanism that control sperm life! Verification of changes will be accomplished by monitoring spermatozoan morphology, uterine and epididymal environments, biochemical substances essential to sperm metabolism and/or inhibition as well as the effect of ambient and/or body temperature upon the accomplishment of capacitation as tested by spermatozoan penetration of the egg in zona pellucida-free hamster oocytes.
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