The reproductive system fetal development of the reproductive system. Each cell in the body contains 23 pairs of chromosomes. With the correct cues, these structures will form either the male or female reproductive tracts follow. Once the testes or ovaries have developed, the reproductive tracts and external genitalia. The reproductive system fetal development of the reproductive system developing male fetus, at 7 weeks testicular cells begin to produce mullerian inhibiting hormone (mih) which causes the mullerian duct to regress. After production, the sperm is stored in the epididymis. After formation in the seminiferous tubule, the sperm move into the epididymis another coiled tube that is roughly 6 meters (20 feet long) epididymis drains into the ductus deferens (or vas deferens) Close inspection of the seminiferous tubules shows that they contain sertoli cells and developing sperm. Immediately outside the seminiferous tubule are the leydig cells (also called interstitial cells) Seminiferous tubules are the site of spermatogenesis.