ABSTRACT
The transforming growth factor beta (TGFβ) field began in the early 1970s with the discovery of sarcoma growth factor; further purification and characterization studies identified this factor as the TGF, which is capable of controlling the growth of a normal cell. At present, TGFβ is a large superfamily of ligands, which regulates multiple body functions. TGFβ ligands signal through SMAD dependent and SMAD independent pathways. Activins are disulfide-linked dimers of inhibin subunits that regulate Sertoli cell number. The glial cell–derived neurotrophic factor (GDNF), a distant member of this family, acts through GFRα1 receptor to maintain the spermatogonial stem cell population for sustained spermatogenesis. MIS signaling is important for male sex-specific differentiation. Thus, integrated and collaborative signaling among various TGFβ family members is central to normal male fertility with functions right from testicular development to germ cell proliferation and differentiation. Any interruption in these signaling channels may result in testicular diseases and male infertility. In this chapter, we cover the TGFβ superfamily of ligands mediating various signaling in testicular development and spermatogenesis.
