The supporting, sustentacular or Sertoli cells present in seminiferous tubules were discovered by Italian histologist, Enricho Sertoli. They are large, elongated and pyramidal cells which have bases adhering to basal lamina (basement membrane) and apices projecting into the lumen of the seminiferous tubules, providing attaching sites to spermatocytes and spermatids. Sertoli cells secrete androgen binding protein (ABP) · which binds to testosterone and transports it; also ABP concentrates testosterone in the seminiferous tubules. Sertoli cells function in response to FSH. They also secrete inhibin which suppresses FSH synthesis by negative feedback. Besides they secrete spermatogenic substances for nourishing and differentiation of cells undergoing spermatogenesis, therefore, Sertoli cells are also called nurse cells.