Maturation of mouse sperm in vitro

Preincubation of sperm in medium for three hours before mixing with ova increased the number of ova fertilized after one hour, thus indicating that sperm maturation occurs in vitro. The presence of cumulus cells increased the proportion of ova fertilized as observed at two and at three hours after the addition of sperm. However, no difference in the proportion of ova fertilized after one hour of incubation was observed using fresh epididymal sperm and ova with or without cumulus cells. No additive effect of cumulus cells and sperm preincubation on fertilization was observed. Sperm preincubation for three hours in the presence of ova either with or without cumulus cells resulted in fertilization similar to that achieved by sperm preincubated in medium alone.