Pars tuberalis and median eminence become apparent.
Fisher DA. 1997. Fetal thyroid function: Diagnosis and management of fetal thyroid disorders. Clinical Obstetrics & Gynecology 40(1):16-31.
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
Koutcherov Y, Mai JK, Paxinos G. 2003 Dec. Hypothalamus of the human fetus. J Chem Neuroanat 26(4):253-70.
Fetal zone accounts for 80-90% of the cortex and is the primary site of growth and steroidogenesis.
Duration: 24 weeks
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.