Apoptosis, spermatogenesis and male infertility.

Apoptosis is an essential physiological process demonstrated to play important roles in diverse physiological processes. As true for several other organs, apoptosis occurs at a high rate in the primary male reproductive organ, testis. Apoptosis is also exhibited by spermatozoa in the human ejaculate. Caspase activation, externalization of phosphatidylserine, alteration of mitochondrial membrane potential and DNA fragmentation are markers of apoptosis found in ejaculated human spermatozoa. These markers appear in excess in sub-fertile men and functionally incompetent spermatozoa. The importance of apoptotic pathway in spermatogenesis and sperm maturation is also indicated by the expression of several markers of this pathway in the testis and epididymis, respectively. This process of regulated cell death serves several important functions in the testis, a few of which include maintaining appropriate germ cell to Sertoli cells ratio, removing defective germ cells and maintenance of overall quality control in sperm production. This review presents an update on the role of apoptosis in male reproduction and fertility, and implications of altered apoptosis in male infertility.