EFFECTS OF CRYSTALLINE ESTRIN IMPLANTS ON THE TIBIA OF YOUNG HYPOPHYSECTOMIZED FEMALE RATS

Abstract

AREPORT HAS RECENTLY been made by this laboratory describing the effect of implants of crystalline estrin on the tibia and costo-chondral junction of young normal female rats (I). After three weeks of estrinization, histological examination of the tibia revealed thick trabeculae that filled the upper fifth of the diaphyseal marrow cavity. Due to our interest in the endocrine factors influencing skeletal growth, which had previously been centered on the role of the hypophyseal growth hormone in young normal and hypophysectomised rats (2, 3, 4), we were much interested in the r6le of the hypophysis in the reaction described above. Therefore, a parallel experi-ment was performed on hypophysectomised rats. Twenty female rats were hypophysectomised at the ages of 54 to 58 days, 10 to be treated with estrin and 10 to serve as controls. Treatment, beginning on the day of operation, consisted of subcutaneous implantation of pellets of a-estradiol dipropionate1 (10 mg.), 1 pellet weekly for 3 weeks.