At approximately day 1

Hypothalamic nuclei and supraoptic tract detected.

Duration: 2 weeks

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

Arginine vasopressin (AVP) detected. Lactrotropes (which produce prolactin) present.

Reference [PubMed Link]

Kaplan SL, Grumbach MM, Aubert ML. 1976. The ontogenesis of pituitary hormones and hypothalamic factors in the human fetus: maturation of central nervous system regulation of anterior pituitary function. Recent Prog Horm Res 32:161-243.

At approximately day 1

Plasma cortisol found in low concentrations.

Reference [PubMed Link]

Kaplan SL, Grumbach MM, Aubert ML. 1976. The ontogenesis of pituitary hormones and hypothalamic factors in the human fetus: maturation of central nervous system regulation of anterior pituitary function. Recent Prog Horm Res 32:161-243.

At approximately day 1

Follicle-stimulating hormone and luteinizing hormone detected.

Reference [PubMed Link]

Kaplan SL, Grumbach MM, Aubert ML. 1976. The ontogenesis of pituitary hormones and hypothalamic factors in the human fetus: maturation of central nervous system regulation of anterior pituitary function. Recent Prog Horm Res 32:161-243.

At approximately day 1

Endogenous fetal thyroid hormone produced, which influences development.

Duration: 26 weeks

Reference [PubMed Link]

Sadler TW. 2000. Susceptible periods during embryogenesis of the heart and endocrine glands. Environ Health Perspect 108 (suppl 3):555-561.

At approximately day 1

Gonadotropes for LH present.

Reference [PubMed Link]

Sadler TW. 2000. Susceptible periods during embryogenesis of the heart and endocrine glands. Environ Health Perspect 108 (suppl 3):555-561.

At approximately day 1

Differentiation of the chromaffin tissue in the medulla begins and continues until 12-18 months after birth.

Duration: 26 weeks

Reference [PubMed Link]

Sadler TW. 2000. Susceptible periods during embryogenesis of the heart and endocrine glands. Environ Health Perspect 108 (suppl 3):555-561.

At approximately day 1

First signs of vascularization.

Duration: 1 week

Reference

Hahn von Dorsche H, Falkmer S. 2000. Ontogenesis of human islets of Langerhans. Review of light and electron microscopic data, immunohistochemical and functional data on fetal development of the endocrine pancreas. Journal of Evolutionary Biochemistry and Physiology 36(6):701-718.

At approximately day 1

Limbs: Primary ossification centers are present in all long bones of the limbs.

Reference

Sadler TW. 2004. Langman’s Medical Embryology. Ninth Edition. Maryland: Lippincott Williams & Wilkins.

At approximately day 5

Prolactin detected.

Reference [PubMed Link]

Kaplan SL, Grumbach MM, Aubert ML. 1976. The ontogenesis of pituitary hormones and hypothalamic factors in the human fetus: maturation of central nervous system regulation of anterior pituitary function. Recent Prog Horm Res 32:161-243.