Spermatogonial Stem Cells

Abstract

Abstract Spermatogonial stem cells are responsible for the maintenance of spermatogenesis in the adult mammal. Knowledge of their regulation is important to understand the initiation of normal spermatogenesis, its recovery after toxic insults, and the modulation of fertility. Information regarding the identification of spermatogonial stem cells and their patterns of self-renewal is extensive and based largely on morphological studies. In contrast, very little of the biochemical and molecular characteristics of these stem cells is known. Unique gene transcripts and proteins, as have been identified in spermatocytes and spermatids (see Chapter 16), have not been described in spermatogonia. Although spermatogonial proliferation and differentiation must be regulated by paracrine and possibly endocrine factors, little is known about how such molecules are involved.