Scatchard plot analysis indicated that the decline in FSH receptor population that occurred in control animals during the 30 day experimental period was significantly retarded by feeding thiouracil, whereas receptors for hCG (LH) were unaffected. Within 1 day of beginning hCG injections on Day 11, ovarian receptors to both FSH and hCG declined precipitously in all animals. The loss in FSH receptors, however, was retarded by thiouracil so that ovarian FSH receptor content remained more than twice that of euthyroid animals during the first 5 days of ovarian cyst induction. This difference disappeared by the end of 20 days of injections by which time extensive ovarian cyst formation had taken place in the hypothyroid animals.

The present work indicates that an enhanced ovarian binding of FSH in hypothyroid animals at the onset of hCG activation of the tissue could explain the excessive follicular response, without ovulation or atresia, which leads to continued growth and fluid accumulation of the cysts.