The molecular basis of sperm capacitation.

Testicular sperm that have undergone spermatogeneis and spermiogenesis appear mature from a morphological standpoint but have acquired neither progressive motility nor the ability to fertilize a metaphase Il-arrested egg. In many species, progressive motility and fertilization competence are acquired during epididyma! transit, but complete fertilization capacity in vivo is only gained upon residence in the female reproductive tract for a finite period of time. The molecular and physiological events that confer on the sperm the ability to feftilize during residence in the female tract are collectively known as pacitation.” These maturational events can also be accomplished in vitro in defined media, the composition of which approximates the environment of the female reproductive tract. Although capacitation was discovered independently by Austin (1951, 1952) and Chang (1951, 1955) nearly one-half century ago, little is known to date about the molecular basis of this important event. This brief review will consider some of the recent findings made toward an understanding of capacitation using in vitro models. The purpose of this review is not to provide an exhaustive analysis of capacitation but is to offer an