Testosterone is the primary male sex steroid. It is
an androgenic steroid synthesised by interstitial Leydig’s cells
in the testes. It is required for spermatogenesis, functional
differentiation of the excurrent ducts of the testes, and the
development of male secondary sexual characteristics.
Androgen binding protein synthesised by Sertoli cells assures
that a high concentration of testosterone is present in the
adluminal compartment of the seminiferous epithelium.