There are a number of adrenal hormonal disorders. Congenital viriliz-
ing adrenal hyperplasiaresults from the deficiency of an enzyme required
for cortisol production. The result is elevated ACTH and secretion of dehy-
droepiandrosterone from the fetal cortex causing masculinization (virilizing)
of the female genitalia. The fetal adrenal cortex is a key component of the
fetal-placental unit. HypercortisolismorCushing’s syndromeis five times
more common in women than men. Cushing’s syndrome may be caused by
a tumor in the corticotrophs of the anterior pituitary (Cushing’s disease), an
adrenal adenoma, or administration of exogenous glucocorticoids. Addi-
son’s diseaseisprimary chronic adrenal insufficiencyand is most often
caused by autoimmune mechanismsleading to atrophy of the adrenal cor-
tex. Elevated ACTH levels lead to hyperpigmentation especially in exposed
areas of the skin or at pressure points such as the elbows and knuckles.
Thethyroid glandis characterized by an extracellular hormone pre-
cursor (iodinated thyroglobulin) stored in its follicles. The follicular cells
endocytose the storage product to form the thyroid hormones [triiodothy-
ronine (T 3 ) and thyroxine (T 4 )]. Scattered between the follicular cells are
32 Anatomy, Histology, and Cell Biology
Adrenal (suprarenal) gland.The gland is covered by a connective tissue capsule and
divided into a cortex containing steroid-producing cells with prominent lipid droplets
and a medulla containing chromaffin cells that secrete catecholamines and neuropeptides.