Retinoic acid signaling in spermatogenesis and male (in)fertility

Spermatogenesis is a very complex, highly organised and timely regulated event, in which spermatozoa originated from undifferentiated spermatogonia that are recruited into the differentiation pathway and meiosis. The spermatogonia entrance into the differentiation pathway is temporally controlled, which in mammals occurs in a progressive non-uniform manner along the tubule at space intervals, allowing spermatozoa production in a continuum. Vitamin A has been implicated for long in the 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 preleptetone to leptotene spermatocyte and therefore the onset of male meiosis, and mediates postmeiotic transitions. Evidences showed that RA plays a broad and encompassing role in regulating and coordinating spermatogenesis. This chapter intends to provide an overview of the role of retinoic acid signalling in spermatogenesis