Protein composition of the luminal fluid and protein synthesis in vitro by the oviducts and uteri of ovariectomized, pro-oestrus and 5-day pregnant rats.

Serum, oviducal and uterine luminal fluid proteins from rats at three different physiological stages of reproduction were analysed by polyacrylamide gel electrophoresis. Protein synthesis and secretion were also studied by short-term incubation of tissue pieces in vitro with radioactive leucine. In ovariectomized animals and 5-day pregnant animals, uterine weight and the protein content of the luminal fluid was significantly lower than in pro-oestrus animals. These differences were much less marked in the oviduct. The protein patterns of oviducal fluid and uterine fluid were significantly different from those of blood serum. However, certain proteins, such as those of 51, 56, 68 and 80 K are clearly derived from blood serum. The protein profile of oviducal fluid and extracts of oviducal tissue showed no obvious differences at the three physiological stages. However, some differences at the three physiological stages were evident in proteins of uterine fluid and in extracts of uterine tissue.