Aspects of the human pharyngeal hypophysis in normal and anencephalic fetuses and neonates and their possible significance in the mechanism of its control.

Aspects of the pharyngeal hypophysis in normal and anencephalic human fetuses and neonates have been described. Volumetric and histological changes in the normal gland similar to those observed previously in the adult are noted. The sellar and pharyngeal hypophyses develop in parallel during intrauterine life, but the latter has reached its maximum development by the time of birth. It is suggested that the control of the pharyngeal hypophysis is mediated through factors in the blood, and that the nature of the control and the vascular route vary at particular periods in both fetal and adult life. From a study of the anencephalic material it appears that the individual cells of the pharyngeal hypophysis are capable of marked response to a specific endocrine imbalance, but the capacity of the pharyngeal hypophysis as a whole to compensate significantly for deficiencies of the sellar adenohypophysis is strictly limited by its inability to hypertrophy to any marked degree.