THE ARREST OF PROLONGED ESTRUS IN “MIDDLEAGED” RATS BY PINEAL GLAND EXTRACT¹²

Abstract

Protein-free bovine pineal extract altered the persistent state of estrus of female rats of post-reproductive age, but had no influence on the regularity of the estrous cycle in adult animals in the doses administered. Ovarian weights were significantly lower in pineal treated animals. Histological examination showed more interstitial tissue, larger though fewer corpora lutea, fewer follicles, and a greater abundance of wheel cells in the ovaries of “middle-aged” treated rat. A possible relationship between the pineal and pituitary gonado-trophic hormone is suggested.