ABSTRACT
Spermatogenesis is a very complex, highly organized and timely regulated event, in which spermatozoa originated from undifferentiated spermatogonia that are recruited into the differentiation pathway and meiosis. Spermatogonia entrance into the differentiation pathway is temporally controlled, which in mammals occurs in a progressive nonuniform manner along the tubule at space intervals, allowing spermatozoa production in a continuum. Vitamin A has long been implicated in spermatogenesis homeostasis and fertility. In the past two decades, new insights evidenced that retinoic acid drives the asynchronous initiation of spermatogonial differentiation, promotes the transition from preleptotene to leptotene spermatocyte and therefore the onset of male meiosis, and mediates postmeiotic transitions. Evidence showed that retinoic acid plays a broad and encompassing role in regulating and coordinating spermatogenesis. This chapter provides an overview of the role of retinoic acid signaling in spermatogenesis.
