What are the embryonic origins of the adrenal gland?

The adrenal gland develops from two different embryonic tissues: the adrenal cortex originates from mesoderm (specifically celomic epithelium), while the adrenal medulla comes from neuroectoderm (neural crest cells).

When does adrenal gland development begin?

Development of the adrenal gland starts in the fifth week of intrauterine life.

How does the adrenal cortex develop?

The adrenal cortex forms in two waves from mesodermal cells. The first wave creates the fetal cortex, which regresses after birth, and the second wave forms the definitive cortex, which becomes the adult cortex.

What is the origin of the adrenal medulla?

The adrenal medulla is derived from sympathochromaffin cells that migrate from the neural crest into the fetal cortex, functioning like postganglionic sympathetic neurons.

What are the layers of the definitive adrenal cortex and when do they form?

The definitive adrenal cortex has three zones: zona glomerulosa and zona fasciculata form at birth, while zona reticularis develops postnatally by the third year.

What is chromaffin tissue and where can it be found?

Chromaffin tissue consists of neural crest-derived cells similar to adrenal medullary cells. It can occur at ectopic sites such as along the abdominal aorta (Organ of Zuckerkandl) or near sympathetic structures.

What are some clinical conditions related to adrenal gland development?

Key clinical correlations include Congenital Adrenal Hyperplasia, caused by enzyme deficiencies like 21-hydroxylase leading to androgen excess, and Pheochromocytoma, a tumor of chromaffin tissue that causes hypertension and sympathetic symptoms.

Adrenal Development – Cortex vs Medulla Origins

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