At approximately day 1

Pars tuberalis and median eminence become apparent.

Reference [PubMed Link]

Fisher DA. 1997. Fetal thyroid function: Diagnosis and management of fetal thyroid disorders. Clinical Obstetrics & Gynecology 40(1):16-31.

At approximately day 1

Perifornal and suprachiasmatic nuclei become differentiated; retinohypothalamic tract is visible; paraventricular nucleus shows distinct subnuclear divisions; median eminence becomes defined, all by week 21.

Duration: 5 weeks

Reference [PubMed Link]

Koutcherov Y, Mai JK, Paxinos G. 2003 Dec. Hypothalamus of the human fetus. J Chem Neuroanat 26(4):253-70.

At approximately day 1

Fetal zone accounts for 80-90% of the cortex and is the primary site of growth and steroidogenesis.

Duration: 24 weeks

Reference [PubMed Link]

Spencer SJ, Mesiano S, Lee JY, Jaffe RB. 1999 Mar. Proliferation and apoptosis in the human adrenal cortex during the fetal and perinatal periods: implications for growth and remodeling. J Clin Endocrinol Metab 84(3):1110-5.