Beschreibung:
AbstractThe mechanism by which uncapacitated epididymal sperm bind to eggs of the golden hamster in vitro has been investigated for the eventual purpose of understanding the nature of the molecular changes that the sperm surface undergoes during capacitation. It was possible to remove bound uncapacitated sperm by washing in medium supplemented with glucuronic acid; other sugars were partially effective or completely ineffective. Pretreatment of sperm with β glucuronidase prevented binding, suggesting that glucuronic acid on the sperm head is involved in binding. If sperm were allowed to bind for 25 minutes, then medium supplemented with glucuronic acid was no longer effective in removing sperm, indicating the nature of binding changes with time.Binding of uncapacitated sperm could also be prevented by removing the epididymal supernatant introduced with the sperm, but it did occur if the eggs were first treated with a purified pronase digest of epididymal supernatant. The active material appears to be oligosaccharide, very likely the carbohydrate portion of epididymal glycoproteins. Glucuronic acid could not be detected in the active fractions of the epididymal supernatant digest suggesting that the binding of uncapacitated sperm depends upon the cooperation of sperm head glucuronic acid and soluble oligosaccharide. The requirement for the soluble factor was not specific, since several glycopeptide fractions derived from pronase digests of either epididymal supernatant or the plasma glycoprotein fetuin caused uncapacitated golden hamster sperm lacking the original supernatant, to bind. However, such sperm would not bind to mouse eggs treated with these fractions.