zona reticularis
Summary
The zona reticularis is the innermost layer of the adrenal cortex that primarily produces androgens (DHEA, androstenedione) under ACTH stimulation. It plays a crucial role in adrenarche and contributes to secondary sexual characteristics, particularly in females where it may be the primary source of androgens.
Detail
The zona reticularis forms the deepest layer of the adrenal cortex, located between the zona fasciculata and the adrenal medulla. Histologically, it consists of irregularly arranged cells with abundant lipofuscin pigment, giving it a darker appearance. The primary function is androgen synthesis, particularly dehydroepiandrosterone (DHEA) and androstenedione, through the action of 17α-hydroxylase/17,20-lyase (CYP17A1). These weak androgens are converted to more potent forms like testosterone and dihydrotestosterone in peripheral tissues. The zona reticularis is stimulated by ACTH and contributes significantly to adrenarche (onset of adrenal androgen production around age 6-8). In females, it represents the major source of circulating androgens since ovarian androgen production is minimal outside of pathological states. Dysfunction can lead to conditions like congenital adrenal hyperplasia (particularly 21-hydroxylase deficiency), premature adrenarche, or androgen excess disorders.
Sources
- Robbins Basic Pathology
- Williams Textbook of Endocrinology
- First Aid for the USMLE Step 1
- Ganong's Review of Medical Physiology
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