SEX HORMONES IN THE BLOOD SERUM OF MARES

Abstract

The blood serum of the pregnant mare has been found to contain large amounts of an ovary-stimulating substance (Cole and Hart, 1). We have some evidence that the urine of pregnant mares is relatively free of this factor. It has been demonstrated that in the human the ovary-stimulating substance is more concentrated in the urine than in the blood serum. These facts suggested the possibility that the substances from the two sources, producing an apparently similar biological reaction in the rat, might be different in chemical or physical composition. Evidence has been obtained by Collip (2) which indicates that the ovary-stimulating material prepared from placenta may not be identical with the hormone in the urine of pregnant women. In the present investigation, an attempt has been made to determine some of the chemical properties of the ovary-stimulating factor present in mare serum during pregnancy. In this paper we have designated as the ovary-stimulating principle, from whatever its source, that factor which stimulates follicle development and produces luteinization in the ovaries of immature female rats after subcutaneous injection. The evidence at hand is still too insufficient to venture a statement regarding the number of hormones concerned in these reactions.