THE EFFECT OF OESTROGEN AND PROGESTERONE ON UTERINE CELL DIVISION AND EPITHELIAL MORPHOLOGY IN SPAYED—HYPOPHYSECTOMIZED RATS

Abstract

Progesterone alters the mitotic and morphological responses of the rat uterus to oestradiol (Clark, 1971). The following experiments were done to see if the pituitary gland, and oestrogen priming, were necessary for the effects of progesterone on the response to a single oestradiol injection. Female Sprague—Dawley rats (200–300 g) were hypophysectomized under Fluothane anaesthesia (Duke, Clark & Askill, 1971) and were then spayed 1 week later under sodium pentobarbitone anaesthesia together with non-hypophysectomized animals of similar age. Hormones were injected starting 1 week after surgery as indicated in Table 1. Twenty-one hours after the last injection each animal was given 0·75 mg demecolcine (Colcemid, Ciba) in water s.c. and killed 4 h later. The success of hypophysectomy was checked by observation of diminished growth rate and adrenal atrophy, and visually at autopsy (Smith, 1930). One horn of each uterus was fixed overnight in formol sublimate. Four to five wax sections