Studies on the hypophysectomized ferret IX—The effect of hypophysectomy on pregnancy and lactation

Abstract

Abstract Animals of several different species have been hypophysectomized during pregnancy. Aschner (1912) found that hypophysectomy in the pregnant dog led to abortion. Pencharz and Long (1931, 1933) in their study of the rat, reported that the fœtuses fail to become implanted if the operation is performed on the fourth day of pregnancy; operation from the seventh to tenth days of pregnancy results in resorption of the fœtuses, while from the eleventh to twentieth day it is followed by death of the mother at the end of a prolonged gestation or by the birth of dead or living young. Selye, Collip, and Thomson (1933, a, b) have extended these studies both on the rat and mouse. They found that hypophysectomy during the second half of pregnancy in the rat does not usually prevent the birth of the young, although gestation is prolonged, nor does it prevent the development of the mammary gland. Milk secretion begins at parturition but ceases within 26 hours. In the mouse, operation during the second half of pregnancy does not lead to abortion, although it was uncertain whether or not the gestation was prolonged because the pregnancies were undated. The mice resembled the rats in that temporary milk secretion occurred. These authors also report (1934) that a guinea-pig hypophysectomized on about the fourteenth day of pregnancy carried a living fœtus when killed 8 days later. Pen­charz and Lyons (1934) have made a more thorough study of the guinea-pig and find that hypophysectomy at 5 weeks pregnant results in re­sorption, but at 6 weeks does not interfere with the course of gestation. Also, as in the rat, a few hours milk secretion follows parturition. Allan and Wiles (1932) found that hypophysectomy in the cat late in pregnancy does not cause interference with the parturition mechanism. Nine animals all delivered living or dead fœtuses. Two litters, however, were definitely premature. White (1933-34) reported abortion following hypophysectomy in the rabbit. The writer (1935) also found that in the cat abortion may result from hypophysectomy. Milk secretion in the cat may occur for longer than in the rat or mouse; in one animal milk could be expressed from the glands as late as 6 days after operation. The present paper deals with the effects of hypophysectomy in the pregnant ferret.