The human fetal adrenal gland-a review of its function and development

The human fetal adrenal gland is morphologically and physiologically unique to primates. For most of fetal gestation, the HFA is solely dedicated to the production of dehydroepiandrosterone sulfate (DHEA-S) and uses low-density lipoprotein (LDL) cholesterol obtained from synthesis of cholesterol from the fetal liver. DHEA-S released by the HFA is used by the placenta as precursors to estrogen synthesis. The HFA is composed of three zones that are functionally distinct-the fetal zone, definitive zone, and transition zone. The HFA, which at mid-gestation is almost as large as the fetal kidney, undergoes rapid involution after birth and has captured the attention of researchers for over a century. Since it was first described in 1911, much of the HFA’s biophysiology, development, and regulation have been elucidated, however, many questions still remain unanswered. An understanding of the regulation of steroid secretion by the HFA is clearly of signal importance to an understanding of the events leading to parturition, of the normal development of the fetus, and of fetal lung maturation.