part of start stage end stage spermatogenic cyst barrier cell Sertoli cell A supporting cell projecting inward from the basement membrane of seminiferous tubules. They surround and nourish the developing male germ cells and secrete androgen binding protein. Their tight junctions with the spermatogonia and spermatocytes provide a blood-testis barrier. zebrafish_anatomy ZFA:0009133 CL:0000216 Sertoli cells TAO:0009133 larval:days 21-29 adult