Adrenal Cortex Zones — FRCA Primary MCQ
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Correct answer: A — Zona fasciculata
The correct answer is A, the zona fasciculata. It is the middle and largest layer of the adrenal cortex and is the principal site of glucocorticoid synthesis, particularly cortisol. Cortisol synthesis is predominantly regulated by ACTH through the melanocortin-2 receptor and cAMP–protein kinase A signalling. The outer zona glomerulosa principally produces aldosterone under renin–angiotensin–aldosterone system and potassium control. The inner zona reticularis principally produces adrenal androgens, including DHEA. The adrenal medulla produces catecholamines rather than corticosteroids, while the fibrous adrenal capsule is not a steroid-secreting endocrine layer. The traditional cortical sequence is glomerulosa–fasciculata–reticularis: ‘salt, sugar, sex’.
Reference: Pignatti E, Flück CE. Adrenal cortex development and related disorders leading to adrenal insufficiency. Molecular and Cellular Endocrinology. 2021;527:111206. https://pubmed.ncbi.nlm.nih.gov/33607267/