Proteins in the uterine secretions of the marsupial Macropus eugenii

Abstract

Proteins in the uterus of the marsupial Macropus eugenii differ qualitatively and quantitatively from proteins in the maternal serum, peritoneal fluid, and lymph. Some similarities are found which suggest that selection occurs as well as synthesis. In delayed and early gestation, the main components are albumin and prealbumin fractions, but during later pregnancy, α- and β-globulins are found as well as the albumins. Progesterone injection to anestrous animals can stimulate the production of secretion, but the secretory condition is maintained in the presence of a developing embryo only after progesterone treatment has been withdrawn. In both normal and progesterone-treated animals total concentration of protein and volume of secretion increases during the gestation period; the nonpregnant uterus always contains less protein than the pregnant. It is suggested that conditions for supporting the growth of the blastocyst and embryo require not only an increase in the total protein content of the uterine fluid but also the production of specific proteins.