tubuli seminiferi contorti vessels vein Leydig cells tubulus seminiferus contortus membrana propria spermatids Leydig cells germinative epithelium spermatogonia primary spermatocytes Sertoli cells acrosome axoneme nucleus ductuli efferentes ductus epididymidis sebaceous glands epidermis corpus spongiosum urethrae HP_img6-16-5 ductus deferens plexus pampiniformis mucosa - folds tunica muscularis glands fibromuscular stroma corpora amylacea corpora cavernosa urethra