SPERM MEMBRANE INCORPORATION INTO OOLEMMA CONTRIBUTES TO THE OOLEMMA BLOCK TO SPERM PENETRATION - EVIDENCE BASED ON INTRACYTOPLASMIC SPERM INJECTION EXPERIMENTS IN THE MOUSE

Mouse oocytes were fertilized by intracytoplasmic sperm injection (ICS I) and reinseminated after the removal of zonae pellucidae at pronucle ar stage or at the 2-cell stage. Although these oocytes were activated normally by ICSI, as evidenced by resumption of meiosis and cortical granule exocytosis, they did not develop oolemma block to sperm penetr ation. They could be penetrated by spermatozoa at pronuclear stage and even at the 2-cell stage. This supports the notion that incorporation of sperm plasma membrane into oolemma contributes to the changes in o olemma that block sperm penetration. (C) 1996 Wiley-Liss, Inc.