The relevance of spontaneous- and chemically-induced alterations in testicular germ cell apoptosis to toxicology

Elimination of germ cells via apoptosis occurs spontaneously under normal p hysiologic conditions and is often heightened after chemical-induced testic ular injury. Though many different apoptosis-related elements have been ide ntified in the testis, the molecular and cellular mechanisms that regulate germ cell apoptosis are not thoroughly understood. In this review, the role of germ cell apoptosis in spermatogenesis and possible key regulators of a poptosis is described. The involvement of the Fas-signaling pathway between Sertoli cells and germ cells is highlighted as a crucial paracrine-signali ng mechanism that responds to both physiologic- or toxicant-induced decline s in the supportive capacity of the testis and reduces the germ cell popula tion accordingly. (C) 2000 Elsevier Science Ireland Ltd. All rights reserve d.