THE GONADOTROPIC ACTIVITY OF THE ANTERIOR PITUITARY OF COCKERELS1

Abstract

Assays of gonadotrophic content of cockerel ant. pituitaries were made using the 96-hr. chick test. A chick unit (C.U.) was established which represented a 35% increase in gonad wt. of the injected animals over the control. There were no significant differences between acetone-dried or fresh pituitaries when these were injected on the basis of equivalent wt. of fresh gland. Gonadotrophic potency was detd. for both entire glands and/mg. wt. of the glands. Total potency ranged from 0.5 C.U. on the 5th day to 8.3 C.U. on the 90th day and the/mg. potency from 0.19 C.U. on day 23 to 1.0 C.U. on day 90. Considerable fluctuation in the/mg. potency of the glands was noted and these variations were compared with the fluctuations in testes weights. The testes wts. expressed as a % of body wt. increased approx. 700% during the period studied. There was a correlation between the/mg. potency curve and that for the testes wts. When there was a plateau in the testes curve the/mg. potency of the glands increased but when the testes wt. increased the curve of mg. potency either decreased or plateaued. These data demonstrate that there is an early secretion by both the ant. pituitary and the testes in the White Leghorn cockerel and that an intimate interrelationship exists between the secretory activity of these glands. A similar assay of pituitaries on mice did not demonstrate satisfactory quantitative differences between age groups.