Endocrine - Adrenal Development

Adrenal

The developing adrenal gland has both an interesting origin and an intruiging fetal role.

The adrenal gland and placenta also act in synergy, and the notes endocrine placenta should also be read.

The 2 adrenal glands (suprarenal gland, glandulæ suprarenales) are named by their anatomical postion sitting above the 2 kidneys (renal). The 2 main parts of the adrenals have different embryonic origins. The inside core adrenal medulla is neural crest in origin. Mesenchyme surrounding these cells differentiates to form a fetal cortex. This fetal cortex is later replaced by the adult cortex. The outside adrenal cortex is derived from mesothelium and can be further divided into 3 distinct layers (zona reticularis, zona fasiculata, zona glomerulosa) each with distinct hormonal functions.

During fetal development, adrenal hormones are involved with the maturation of the lung and other developing systems.

Historic Embryology - Endocrine
1903 Islets of Langerhans \| 1903 Pig Adrenal \| 1904 interstitial Cells \| 1908 Pancreas Different Species \| 1908 Pituitary \| 1908 Pituitary histology \| 1911 Rathke's pouch \| 1912 Suprarenal Bodies \| 1914 Suprarenal Organs \| 1915 Pharynx \| 1916 Thyroid \| 1918 Rabbit Hypophysis \| 1920 Adrenal \| 1935 Mammalian Hypophysis \| 1926 Human Hypophysis \| 1927 Adrenal \| 1927 Hypophyseal fossa \| 1930 Adrenal \| 1932 Pineal Gland and Cysts \| 1935 Hypophysis \| 1935 Pineal \| 1937 Pineal \| 1935 Parathyroid \| 1940 Adrenal \| 1941 Thyroid \| 1950 Thyroid Parathyroid Thymus \| 1957 Adrenal

| Lecture - Neural Crest Development | original page

Richly vascularized - arterioles passing through cortex, capillaries from cortex to medulla, portal-like circulation
Fetal Cortex - produces a steroid precursor (DEA), converted by placenta into estrogen
Adult Medulla - produces adrenalin (epinephrine), noradrenaline (norepinephrine)
Fetal adrenal hormones - influence lung maturation

Adrenal cortical hormones - (steroids) Cortisol, Aldosterone, Dehydroepiandrosterone

zona glomerulosa - regulated by renin-angiotensin-aldosterone system controlled by the juxtaglomerular apparatus of the kidney.
zona fasciculata - regulated by hypothalamo-pituitary axis with the release of CRH and ACTH respectively.

Adrenal medullary hormones - (amino acid derivatives) Epinephrine, Norepinephrine

Adrenal Development

Week 10 adrenal gland

Fetal Adrenals - fetal cortex later replaced by adult cortex
Week 6 - fetal cortex, from mesothelium adjacent to dorsal mesentery; Medulla, neural crest cells from adjacent sympathetic ganglia
Adult cortex - mesothelium mesenchyme encloses fetal cortex

Adrenal Cortex

Late Fetal Period - differentiates to form cortical zones
Birth - zona glomerulosa, zona fasiculata present
Year 3 - zona reticularis present

Endocrinology - Adrenal Cortex Development

Adrenal Medulla

neural crest origin, migrate adjacent to coelomic cavity, initially uncapsulated and not surrounded by fetal cortex, cells have neuron-like morphology
2 cell types - secrete epinepherine (adrenaline) 80%; secrete norepinepherine (noradrenaline* 20%

Media:Adrenal_medulla.mov