Sources of Progestins in the Pregnant Cow

Abstract

Progesterone and [DELTA]4-pregnene-20[beta]-ol-3-one were assayed, using paper chromatography and UV spectra. Neither progestin was detected in the placental or uterine venous blood of a Jersey heifer pregnant 258 days. The blood, adrenals, and testis of the fetus were negative for progestins. The ovaries contained an estimated 50 [mu]g of progesterone (adrenals < 10 [mu]g) and 5 [mu]g of [DELTA]4-pregnene-20[beta]-ol-3-one. Six additional assays of cow placentae have been negative for progesterone. Corpora lutea (5 assays involving 3 each) contained approximately 90% of the progesterone and all of the [DELTA]4-pregnene-20[beta]-ol-3-one found in the ovaries of cows. The remaining progesterone was in the ovaries from which the corpora lutea were removed. Progesterone ranged from 614 to 15.2 [mu]g/g in luteal tissue. The lowest concentration was from late-pregnant and the highest from nonpregnant cows.