Somatic Cells in the Anuran Testis.

BACKGROUND: The anuran testis is a heterogeneous organ composed of germline and somatic cells mainly derived from the coelomic epithelium (Sertoli cells) and mesonephros (Leydig cells), which together regulate spermatogenesis and testicular architecture. SUMMARY: We provide an integrative overview of the developmental origin, structure, and function of somatic cells in evolutionary primitive and advanced anurans, with comparisons to other vertebrates. Initially bipotential gonad differentiates into testes by forming seminiferous cords and tubules composed of gonocytes and Sertoli cells, and a peritubular compartment containing Leydig cells. A distinctive feature of anurans is the continued proliferative capacity of Sertoli cells and their ability to form cysts in which spermatogenesis occurs within adult seminiferous tubules. Although key genes involved in testis differentiation are broadly conserved across vertebrates, their timing and functional roles often differ in anurans, where gonadal development is strongly influenced by steroid hormones, a feature typical of anamniotes. KEY MESSAGES: Vertebrate testes are homologous and share a basic organizational plan, differing mainly in cystic spermatogenesis in anamniotes versus tubular spermatogenesis in amniotes. While somatic cell lineages are largely conserved, anurans exhibit increased complexity in molecular regulatory pathways and remain understudied with respect to the developmental origins of specific cell populations.