A pregnancy-specific protein in the bovine uterus

Abstract

An antibody was developed to a pregnancy-specific protein in the cow. This protein is present by 15 days postmating in the uterine endometrium and uterine flushings from uteri of cows containing a blastocyst, but is not present in uterine endometrium and flushings obtained from uteri of cows 15 days postmating in which no blastocysts were found. The cow blastocyst is 10-25 mm in length at 15 days postmating. This pregnancy-specific protein is also present in the uterine endometrium of cows at 48 days of pregnancy. This protein was not detectable in plasma, liver, kidney, spleen and muscle tissue from pregnant cows. The identity and composition of this pregnancy-specific protein is not known. It has a molecular weight of 50-60,000 and migrates on agarose more slowly than albumin (R.f. = 0.35). Indirect estimates of quantity indicate the uterine endometrial proteins of cows at 15 days of pregnancy contain about 1 percent or less of the pregnancy-specific protein.