gonadotropins; lh/fsh/itt; t; sperm

Male HPG axis Human spermatogenesis requires both FSH and µmolar locally-secreted intratesticular paracrine T - 100X serum concentration is normal - 10-20X serum will do and is achievable with hCG 500 iU 2-3X/week Can't be sustained by µmolar nmolar circulating endocrine T