BIOGENESIS OF THE ESTROGENS: THE FAILURE OF CHOLESTEROL-4-C14TO GIVE RISE TO ESTRONE IN THE PREGNANT MARE

Abstract

A pregnant mare was injd. intrajugularly with cholesterol-4-Cl4 and the excreta were examined for Cl4-labeled metabolic products. Radioactivity was excreted in urine, feces and saliva. The steroid-containing portion in the urine extracts yielded estrone which was non-radioactive. The neutral ketonic and non-ketonic fractions contained considerable Cl4. it is thus concluded that in the pregnant mare cholesterol administered to the maternal circulation in this manner does not give rise to estrone, but very probably functions as a precursor of pregnane and allopregnane derivatives.