Hypophysectomy of the Immature Guinea-Pig and the Ovarian Response to Gonadotrophins

Summary. A 50% decrease in ovarian weight occurred within 4 to 6 days after hypophysectomy, accompanied by a gradual reduction in the total number of normal vesicular follicles and the disappearance of all the largest follicles. There was an initial accumulation of atretic follicles followed by a reduction in their numbers as they became absorbed in the ovarian stroma. Attempts to induce follicular stimulation to a degree which was adequate for ovulation and corpus luteum formation were unsuccessful. A constant feature of the ovarian response to gonadotrophins from a variety of sources consisted of a `luteinization' of atretic follicles and stromal tissue.