ACTH also regulates secretion of these cells, although other factors such as cortical androgen-stimulatinghormone, released from the pituitary, may also beinvolved. The zona reticularis, the deep layer of the cortex, secretes the adrenal androgens dehydroepiandrosterone (DHEA) and androstenedione, as well as small amounts ofestrogens and some glucocorticoids. The zona fasciculata, the middle and widest layer, constitutes about 75 per cent of the adrenal cortex and secretes the glucocorticoids cortisol and corticosterone, as well as small amounts of adrenal androgens and estrogens. The secretionof these cells is controlled in large part by the hypothalamic-pituitary axis via adrenocorticotropic hormone (ACTH).ģ. The secretion of these cells is controlled mainly by the extracellular fluid concentrations of angiotensinII and potassium, both of which stimulate aldosterone secretion.Ģ. These cells are the only ones in the adrenal gland capable of secreting significant amounts of aldosterone because they contain the enzyme aldosterone synthase, which is necessary for synthesis of aldosterone. The zona glomerulosa, a thin layer of cells that lies just underneath the capsule, constitutes about 15 per cent of the adrenal cortex. Figure 77–1 shows that the adrenalcortex is composed of three relatively distinct layers:ġ. The Adrenal Cortex Has Three Distinct Layers. Synthesis and Secretion of Adrenocortical Hormones

Adrenal gland hormone synthesis