Adrenal gland
The adrenal glands are named for their location relative to the kidneys. The term "adrenal" comes from "ad-" (Latin, "near") and "renes" (Latin, "kidney"). Similarly, "suprarenal", as termed by Jean Riolan the Younger in 1629, is derived from the Latin "supra" () and "renes" (). The suprarenal nature of the glands was not truly accepted until the 19th century, as anatomists clarified the ductless nature of the glands and their likely secretory role – prior to this, there was some debate as to whether the glands were indeed suprarenal or part of the kidney.
Adrenal gland
Adrenal cortex tissue is derived from the intermediate mesoderm. It first appears 33 days after fertilisation, shows steroid hormone production capabilities by the eighth week and undergoes rapid growth during the first trimester of pregnancy. The fetal adrenal cortex is different from its adult counterpart, as it is composed of two distinct zones: the inner "fetal" zone, which carries most of the hormone-producing activity, and the outer "definitive" zone, which is in a proliferative phase. The fetal zone produces large amounts of adrenal androgens (male sex hormones) that are used by the placenta for estrogen biosynthesis. Cortical development of the adrenal gland is regulated mostly by ACTH, a hormone produced by the pituitary gland that stimulates cortisol synthesis. During midgestation, the fetal zone occupies most of the cortical volume and produces 100–200 mg/day of DHEA-S, an androgen and precursor of both androgens and estrogens (female sex hormones). Adrenal hormones, especially glucocorticoids such as cortisol, are essential for prenatal development of organs, particularly for the maturation of the lungs. The adrenal gland decreases in size after birth because of the rapid disappearance of the fetal zone, with a corresponding decrease in androgen secretion.