The effect of removing surface-associated proteins from viable chicken spermatozoa on sperm function in vivo and in vitro

When chicken spermatozoa were diluted in isotonic or hypertonic solutions, sperm surface-associated proteins were lost to the medium, quantitatively more protein being lost to medium of higher osmotic strength. The proteins which were removed from the spermatozoa were also found within chicken seminal plasma, but at different relative concentrations, thus demostrating selective association of only certain seminal proteins with the spermatozoa. The removal of these proteins occurred with only minimal damage to the spermatozoa, as judged by sperm motility, ATP content and ability to exclude eosin. Spermatozoa treated with hypertonic solutions were unable to reach the freshly ovulated egg in the infundibulum and could not be found within the uterovaginal sperm storage tubules after uterovaginal insemination. However, if inseminated directly into the uterovaginal junction, spermatozoa were able to enter the sperm storage tubules, suggesting that the treatment limited their ability to migrate through the vagina. Loss of sperm fertilizing ability following simple centrifugation and washing treatments appears to result from removal of surface-associated proteins.