RELATIONSHIP OF GONAD-STIMULATING ACTIVITY OF FEMALE DOMESTIC FOWL ANTERIOR PITUITARIES TO REPRODUCTIVE CONDITION

Abstract

Detns. were made of the gonadotrophic potency of unfractionated ant. pituitary powders from Rhode Island Red and White Leghorn hens as well as from a group of hens of mixed breeds. The pituitary powders were classified according to whether the ovarian follicular type was maturing, mature, regressing or quiescent. The response of the uterus of the immature mouse was used as a measure of gonad-stimulating activity; a mouse uterine unit (M.U.U.) being defined as the smallest amount of pituitary powder effecting a 100-150% increase in the avg. wt. of the uteri of injected animals over that of the uteri of controls. In general, ant. pituitaries from hens with follicles in the regressive or quiescent phase show a higher gonad-stimulating effect than those from hens in full ovulating condition. The avg. values of the M.U.U. for 4 groups of hens were 4.5, 3.5 and 2.9 mg. for pituitaries from birds with mature, regressing and quiescent follicles respectively. No significant difference was found between the effectiveness of pituitaries from Rhode Island Red and White Leghorn hens obtained at the same time of the yr. The lowest potency was found in glands of laying birds collected in the fall.