Anterior pituitary, in response to gnrh, releases fsh (follicle stimulating hormone) and lh (luteinizing hormone), the gonadotropins, into plasma. Effect of fsh & lh depends on the sex of the individual. In both sexes, the hypothalamus secretes low levels of gnrh for 12 more years. Gabanergenic (ipsp) neurons inhibit the hypothalamic release of gnrh. At puberty gnrh increases, the gonadotropins re-activate cells in the testes (leydig & sertoli) & spermatogenesis begins. Dht, dihydrotestosterone & testosterone from fetal leydig cells in fetal testes masculinities the fetus. T stimulates upregulation of androgen (male steroids) receptors throughout the body. The t at puberty binds to an androgen receptors, activating the development of secondary sex. Seminiferous tubules of the testes house sperm at various stages of maturation. Leydig cells t production helps sperm get created. Sertoli cells, sperm development (nurse cells) helps sperm mature. T is aromatized to estradiol as it enters sertoli cells.