Development and Function of the Adrenal Cortex and Medulla in the Fetus and Neonate

Abstract The human adrenal glands consist of two parts, the cortex and the medulla, which differ in origin, composition, and function. The adrenal cortex, the outer part, derives from the mesoderm, is composed of steroidogenic cells, and synthetizes steroid hormones [aldosterone, cortisol, and dehydroepiandrosterone/dehydroepiandrosterone sulfate (DHEA/DHEAS)]. The adrenal medulla, the inner part, derives from the neuroectoderm, is composed of chromaffin cells, and synthetizes catecholamines (adrenaline and noradrenaline). The process that forms the adrenals begins early in embryogenesis and continues into adult life. Appropriate development and function of these glands are essential for several processes that can affect the fetus, the neonate, and even the future adult. They are an important element for fetal maturation, and hence for the transition from fetal to neonatal life. After birth, they play an essential role in survival, adaptive responses to stress, fluid homeostasis, and development of secondary sexual characteristics.