| Abstract: | Fifteen human oocytes incubated with spermatozoa for 24 hr and cultured for 1-3 days were examined by scanning electron microscopy. Five of the oocytes were preovulatory (3 uncleaved and 2 cleaved after culture) and 10 nonovulatory. There was a wide variation in the number of spermatozoa attached to or penetrating the zona pellucida of the oocytes. On preovulatory oocytes, spermatozoa were observed, ranging in numbers from a few to about 50, while on nonovulatory oocytes they numbered from a few to several hundred. Oocytes may differ with respect to sperm-binding sites on the zona pellucida. After incubation in vitro, spermatozoa with abnormal forms were rarely observed on the oocytes or in between corona cells. Selection of spermatozoa may take place on their interaction with oocytes/cumulus corona cells. |
