Patricio Morales¹ and Miguel Llanos²

¹ P. Catholic University of Chile, Faculty of Biological Sciences. P. O. Box 114-D. Santiago, Chile.

²INTA, University of Chile, P. O. Box 138-11. Santiago, Chile.

1. .ABSTRACT

Mammalian spermatozoa are not able to fertilize an oocyte upon ejaculation. To gain fertilizing ability, spermatozoa must, either in vivo or in vitro, undergo a process termed capacitation. Since a reliable marker for capacitation does not exist, it is considered that this process is completed when the spermatozoa are able to undergo acrosomal exocytosis. Therefore, the AR has become one of the best studied events in the process of fertilization. Fertilization is a very complex phenomenon, involving sequential interactions between the fertilizing spermatozoon and cumulus oophorus, ZP, and oolemma. The AR may be playing a key role in penetration of spermatozoa through these egg vestments.