Anatomy of the Adrenal Glands

Abstract

The adrenal (or suprarenal) glands, two in number, are located retroperitoneally atop the superiomedial pole of each kidney. Each gland weighs approximately 3 to 5 g and measures 2.5 × 0.6 cm. The left adrenal is larger and assumes a crescentlike shape in contrast to the right, which is triangular. Each adrenal gland consists of two portions—an outer cortex and an inner medulla. These two parts differ in their embryology, histology, and secretory functions. The adrenal cortex is derived from the celomic epithelium (mesoderm), whereas adrenal medulla is derived from the neural crest (neurectoderm). The adrenal cortex is composed of three clearly defined zones with separate secretory activity, whereas the adrenal medulla is composed of chromaffin tissue with histological characteristics of sympathetic ganglia. The adrenal cortex synthesizes steroids (mineralocorticoids, glucocorticoids, and sex steroids), whereas the medulla synthesizes catecholamines.