EFFECTS OF OVARIECTOMY ON THE FOLLICLE-STIMULATING AND INTERSTITIAL-CELL-STIMULATING CONTENT OF THE ANTERIOR PITUITARY OF THE RAT1

Abstract

Anterior pituitaries from normal rats and ovariectomized rats of various postoperative ages have been assayed in immature hypophyscctomized female rats for follicle-stimulating (FSH), interstitial-cell-stimulating (ICSH) and growth-stimulating (GH) activity. Histological criteria have been used to determine FSH and ICSH activities, and width of the tibial epiphyseal cartilage plate used as an index of GH activity. The pituitary FSH content increased markedly (3- to 4-fold) within 7 days following ovariectomy and continued to increase progressively when tested at 2 weeks, one month and 2 months postoperative. No further increase was found after a 4 or 9 month period. The pituitary ICSH content likewise showed a marked increase (approximately 4 times the normal level) at 7 days postoperative, and continued to increase progressively up to 9 months, the longest period tested. GH content remained the same in pituitaries of both normal rats and ovariectomized rats for 2 months after the operation, but a slight decrease in GH content was found with a 4 and 9 month postoperative period.