Fractionation and comparison of proteins from bovine uterine fluid and bovine allantoic fluid.

Serum, allantoic fluid and uterine washings obtained from cows at various stages of pregnancy were fractionated by gel filtration and the fractions compared by electrophoretic and immunological methods. Several proteins were detected in uterine washings which were not found in serum. Some of these proteins were sensitive to the experimental conditions used for concentrating the uterine washings, being irreversibly adsorbed onto the glass containers on freeze drying. The number and imtensity of the "uterine-specific" proteins varied with the stage of pregnancy, changes in the electrophoretic patterns being detected just prior to rapid elongation of the embryo and at a stage when luteolysis would have occurred in the unmated cow. Many of the "uterine-specific" proteins were also detected in allantoic fluid.