Functional prenatal development of anencephalic and normal anterior pituitary glands. In human and experimental animals studied by peroxidase-labeled antibody method.

In order to investigate the influence of the central nervous system on the functional differentiation of the fetal anterior pituitary gland, the pituitary gland of anencephalic and normal fetus was studied by the peroxidase-labeled antibody method for the localization of various hormones. The only abnormality of pituitary endocrine cells in anencephaly was a marked decrease of ACTH cells. In the normal development, ACTH appeared as the earliest hormone in 5 weeks. And all other hormones were seen in 13 weeks. The reason for the decrease of ACTH cells in anencephaly was speculated to be a suppression at an early developmental life. The experimental observations done in rats using MAM might support this speculation. The adrenal glands of anencephalus showed atrophy of the fetal cortex which was considered to correlate with the decrease in number of ACTH cells. Absence of the histochemical activity of alkaline phosphatase in the permanent cortex of anencephaly may indicate absence or inadequate stimulation by fetal ACTH. Further experimental studies in suppression of the central nervous system in early developmental life seemed to confirm the above speculation in functional differentiation of the fetal pituitary and adrenal glands.