Editing Endocrine system (section)

===Adrenal glands===
The fetal [[adrenal cortex]] can be identified within four weeks of [[gestation]]. The adrenal cortex originates from the thickening of the intermediate [[mesoderm]]. At five to six weeks of gestation, the [[mesonephros]] differentiates into a tissue known as the genital ridge. The genital ridge produces the steroidogenic cells for both the gonads and the adrenal cortex. The adrenal medulla is derived from [[Ectoderm|ectodermal cells]]. Cells that will become adrenal tissue move retroperitoneally to the upper portion of the mesonephros. At seven weeks of gestation, the adrenal cells are joined by sympathetic cells that originate from the neural crest to form the [[adrenal medulla]]. At the end of the eighth week, the adrenal glands have been encapsulated and have formed a distinct organ above the developing kidneys. At birth, the adrenal glands weigh approximately eight to nine grams (twice that of the adult adrenal glands) and are 0.5% of the total body weight. At 25 weeks, the adult [[adrenal cortex]] zone develops and is responsible for the primary synthesis of [[Steroid|steroids]] during the early postnatal weeks.