STUDIES OF SPERM CAPACITATION AND HYPERACTIVATION

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The goals of this research are to elucidate the relationship of hyperactivated sperm motility to sperm capacitation and fertilization and to examine molecular events associated with the onset of hyperactivation. Only small percentages of human spermatozoa have been observed undergoing hyperactivation in vitro, yet it is assumed on the basis of studies of several mammalian species, that hyperactivation precedes fertilization in vivo. The hamster will be used as a model system because hamster spermatozoa may be induced to hyperactivate in a defined medium in vitro and may also be observed moving towards the site of fertilization in the oviduct. The methods to be used are comparative videoanalysis of the onset of hyperactivated motility in vitro and in vivo, using labeled lectins and monoclonal antibodies to monitor cell surface changes during hyperactivation and to identify membrane components associated with hyperactivation, and comparing the success of non-hyperactivated spermatozoa with that of hyperactivated spermatozoa in achieving the site of fertilization in the oviduct and penetrating the cumulus matrix. Information learned from the hamster system could eventually be applied to the understanding of human fertilization, e.g. whether normal spermatozoa must be able to hyperactivate under the correct environmental conditions and how hyperactivation might be prevented as a contraceptive technique.