Epididymal
sperm
-
initially nonmotile
-
get coated with proteins from the epididymis
These proteins are removed by incubation
in media that lowers the pH of 8+ with high K+ and
polyamines as in semen to < pH 7 after deposition into the vagina. The
removal of these proteins and activation of the sperm is capacitation.
The acrosome reaction which removes
the outer acrosomal membrane occurs in or on the "jelly coat" of the egg.