Effects of purification or split ejaculation of semen and stimulation of spermatozoa by caffeine on their motility and fertilizing ability with the use of zona-free hamster ova.

Purification of semen with Sephadex G-50 medium powder or bovine serum albumin (BSA) (20% in medium) columns increases the percentage of motility. Spermatozoa that passed a BSA column or a Sephadex column have significantly higher velocity than unmanipulated spermatozoa. Caffeine (7 mM) stimulation did not show any effect on motility. Neither purification procedures nor stimulation with caffeine improved the in vitro fertilization capacity of capacitated spermatozoa, as determined by interaction with zona-free hamster ova. No difference in in vitro fertilizing capacity could be demonstrated between the first and the last fractions of split ejaculates. After grouping the fractions according to sperm counts, fractions with higher total (motile) sperm counts, and fractions with higher sperm counts had significantly higher fertilization percentages than the fractions with lower (motile) sperm counts.