ABSTRACT
The adrenal gland is made of two parts, the cortex and the medulla, which have different embryonic origins. By four tofiveweeksof fetal life, cells from themesoderm aggregate to form a primitive cortex between the posterior part of the dorsal mesentery and the gonadal ridge (1). Shortly thereafter, this primitive cortex becomes surrounded by a narrow band of cells termed permanent cortex. By seven to eight weeks of fetal life, the primitive cortex is invaded by chromaffin cells that develop rapidly and eventually replace most of the primitive cortical cells, forming the medulla (1). At that time, the adrenal gland is in close relation with the cranial part of the primitive kidney and not far from the genital ridge.
