EXPERIMENTS ON THE CONTRIBUTION OF SOMATOTROPHIN TO PRENATAL GROWTH IN THE RAT

Abstract

Hypophyseo-privus in a fetal rat induced by decapitating the fetus in utero retards fetal growth. This effect can be prevented by injected somatotrophin. These observations substantially support the view that in the normal rat shortly before birth the fetal somatotrophin from the developing hypophysis governs in part the prenatal growth which occurs at that time. Although complete hypophysectomy of a pregnant rat retards the growth of fetuses, the manner of its action is obscure. In an individual litter, combined hypophysectomy of the mother and hypo-physeoprivus in a fetus retards fetal growth but not to any greater extent than hypophysectomy of the mother without hypophyseoprivus in the fetus. In the intact fetus injections of somatotrophin do not accelerate fetal growth, presumably because ample fetal somatotrophin from the developing hypophysis is present.