A factor(s) produced by Sertoli cells stimulates androgen biosynthesis by Leydig cells in neonatal rats

Using a coculture system, we have studied the local action of Sertoli cells on Leydig cell function. The results show that (i) both LH and FSH have equal potency to stimulate testosterone biosynthesis by fetal and neonatal testicular cells in an age-dependent manner, the maximum stimulation is observed between D3 and D5. (ii) An FSH-dependent factor(s) secreted by Sertoli cells increases the basal and/or LH-stimulated Leydig cell androgen production. (iii) The Sertoli cell-stimulating factor(s) is not a steroid or other small molecule, but a heat-labile peptide.