Demonstration of a nonestrogenic gonadal inhibitor produced by the ovary of the brown Leghorn

Abstract

In the brown Leghorn female, as in most birds, the right gonad is rudimentary. Removal of the left functional ovary results in the growth and differentiation of the rudimentary gonad into a testicular organ or, less frequently, into an ovotestis or ovary. Two experiments were designed to test the hypothesis that the ovary produces a substance (or substances), other than estrogen, which inhibits the development of the right gonad: 1. (1) An extract of pullet ovaries, free from significant amounts of estrogen and androgen (i.e., amounts capable of inhibiting the development of the right gonad in ovariectomized birds or capable of causing feminization of the plumage and stimulation of comb growth, respectively), significantly depressed the growth and differentiation of the right gonad in ovariectomized birds. 2. (2) Autotransplants of the ovary into the portal field (gizzard) resulted in hepatic inactivation of estrogen and complete or partial inhibition of the right gonad. The results of these experiments demonstrate that the ovary of the brown Leghorn produces a substance, other than estrogen, which can inhibit the growth and differentiation of the right rudimentary gonad. It seems probable that this inhibitory substance, or substances, may be another example of organ-specific inhibition, originally postulated by Rose (1952) and Weiss (1952) and subsequently demonstrated by several investigators.