The Effect of Daily Transplants of the Anterior Lobe From Gonadectomized Rats on Immature Test Animals

Gonadotropin Levels in Lactating Rats: Effect of Ovariectomy12

“…In the rat, castration is followed by the appearance and development of "castration cells" in the anterior pituitary (Addison, 1917;Desclin, 1947). This change in pituitary morphology is described as an increase in the number and size of the basophilic cells and is accompanied with an elevation in gonadotropic potency (Engle, 1929;Evans and Simpson, 1929). Desclin (1947) demonstrated that constant nipple stimulation in the absence of milk loss prevented the appearance of castration cells in rats ovariectomized following parturition.…”

Adrenal Involvement in Determining the Time of Onset of Puberty in the Rat1

“…Pituitaries from gonadectomized rats have greater growth effects on ovaries of immature rats than pituitaries from intact rats which led to the demonstration of increased LH and FSH in ovariectomized animals (53,55). These high gonadotropin (GTH) levels are inhibited by estrogenic compounds (137), but not by progesterone itself (171, 178).…”

Anterior pituitary changes referable to the reproductive hormones, and the influence of the thyroid and the adrenals on genital function.

“…In contrast to the findings regarding the gonad-stimulating capacity of the anterior pituitary during pregnancy, is a well established fact that after castration in the rat the potency is greatly increased. The hypophysis of a castrated donor rat causes a response in the test animal which is more rapid and of greater magnitude than that of non-castrate donors (Engle, 1929). The castration of the donors either before puberty or in adult life is equally satisfactory in eliciting this response, causing an increase of ovarian weight of from four to nine times over those which had received implants from normal animals.…”

“…When the the increased gonadokinetic action of the anterior lobe of gonadectomized rats was demonstrated, it was natural to link the increased potency with the increased number of signet-ring basophiles, and refer to them as the cells of origin, in the rat, of the increased gonadokinetic principle (Engle, 1929). Emanuel (1931) reports a greater potency in the implants from gonadectomized rats, but states that the implant of the castrated rat causes greater luteinization of the ovary of the recipient.…”