[Apoptosis during spermatogenesis and in ejaculated spermatozoa: importance for fertilization]

It has become clear in recent years that programmed cell death occurs spontaneously in the cycle of the seminiferous epithelium. Induced germ cell apoptosis occurs at specific stages of the spermatogenic cycle and the existence of supracellular control of germ cell death during spermatogenesis has been documented. If apoptosis is a key phenomenon in the control of sperm production, the existence and role of apoptosis in ejaculated sperm cells remain controversial. Apoptosis - as determined by DNA fragmentation (Tunel) and ultrastructural analysis - is abnormally frequent in the sperm cells of the ejaculate of sterile men. In this review, we discuss the possible origins of DNA damage in ejaculated human spermatozoa and the consequences of these DNA damage if the apoptotic spermatozoa is used for ICSI. Percentages of DNA fragmentation in human ejaculated sperm correlated with fertilization rates after FIV or ICSI assay. Detection of DNA fragmentation in human sperm could provide additional information about the biochemical integrity of sperm and may be used in future studies for fertilization failures not explained by conventional sperm parameters. However, the analysis of other molecular markers of apoptosis (Fas, Annexine V.) is now necessary to assess the role of apoptosis in human ejaculated sperm cells.