At approximately day 1

Thyroid-stimulating hormone detected.

Reference [PubMed Link]

Fisher DA, Dussault JH, Sack J, Chopra IJ. 1976. Ontogenesis of hypothalamic-pituitary-thyroid function and metabolism in man, sheep, and rat. Recent Prog Horm Res 33:59-116.

At approximately day 1

Melanotropin 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

Somatostatin 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

Growth 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

Thyroid hormone synthesis begins.

Duration: 2 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

Insulin cells have rough granules; lymphocytes can be identified; first signs of innervation.

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

Pancreatic polypeptide detected.

Reference [PubMed Link]

Piper K, Brickwood S, Turnpenny LW, Cameron IT, Ball SG, Wilson DI, Hanley NA. 2004 Apr. Beta cell differentiation during early human pancreas development. J Endocrinol 181(1):11-23.

At approximately day 1

Parathyroid glands reach their final destination in the neck.

Reference

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

At approximately day 4

Iodide concentrating begins.

Reference [PubMed Link]

Shepard TH. 1967. Onset of function in the human fetal thyroid: Biochemical and radioautographic studies from organ culture. Journal of Clinical Endocrinology & Metabolism 27(7):945-958.

At approximately day 4

Hematopoietic stem cells colonize bone marrow.

Reference [PubMed Link]

Flaws JA, Sommer RJ, Silbergeld EK, Peterson RE, Hirshfield AN. 1997. In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces genital dysmorphogenesis in the female rat. Toxicology & Applied Pharmacology 147(2):351-362.