THE EFFECT OF NORETHYNODREL ON THE OVARIES AND PITUITARY GLAND OF ADULT FEMALE RATS

Abstract

SUMMARY Prolonged treatment with norethynodrel at a dose level sufficient to cause sterility did not consistently lead to blocking of ovulation. The ovaries of some of the animals were devoid of corpora lutea, while those of others contained variable numbers at different stages of development and regression. None of the treated animals, however, possessed as many corpora lutea as did their oil-injected controls. The treatment also induced a variable degree of follicular inhibition. Typical and regular oestrous cycles were abolished. The incidence of corpora lutea formed during the period of injection was slightly greater in animals housed with males than in those kept isolated. Although coitus was not followed by a period of pseudopregnancy, as judged by vaginal smears, most of the mated animals possessed corpora lutea resembling those of pseudopregnancy. The pituitary gland of the norethynodrel-treated animals was heavier than that of their controls, due largely to an increase in the volume of tissue occupied by chromophobe cells. The proportion of basophil cells was lower, while that of eosinophil cells remained unchanged.