At approximately day 1

Mullerian ducts regress.

Duration: 2 weeks

Reference

Larsen WJ. 1997. Human Embryology. New York: Churchill Livingstone Inc.

At approximately day 1

Leydig cells differentiate from mesenchymal somatic cells and begin to produce testosterone (T). Fetal T production is stimulated by human chorionic gonadotrophin.

Reference [PubMed Link]

Rabinovici J, Jaffe RB. 1990. Development and regulation of growth and differentiated function in human and subhumand primate fetal gonads. Endocrine Reviews 11(4):532-557.

At approximately day 4

Anti-Mullerian hormone detected in Sertoli cells.

Reference [PubMed Link]

Rajpert-De Meyts E, Jorgensen N, Graem N, Muller J, Cate RL, Skakkebaek NE. 1999. Expression of anti-Mullerian hormone during normal and pathological gonadal development: association with differentiation of Sertoli and granulosa cells. Journal of Clinical Endocrinology & Metabolism 84(10):3836-3844.

At approximately day 4

Sertoli cells produce anti-Müllarian hormone (AMH), and continue production until puberty.

Duration: 30 weeks

Reference

Moore KL, Persaud TVN. 1998. The Developing Human: Clinically Oriented Embryology. 6th ed. Philadelphia: WB Saunders Co.