In-vitro fertilization of preovulatory human eggs.

Preovulatory eggs were aspirated from the ovaries of women 36-38 h after hCG and incubated with washed sperm suspensions for 3 or 6 h; 5 out of 9 eggs were fertilized. Sperm penetration into the ooplasm and decondensation of the male chromatin was observed by 3 h, and an early pronucleate egg was found by 6 h, suggesting that human spermatozoa may become capacitated in vitro in 3-4 h.