Protein patterns of luminal fluids and mucosal tissue extracts of the uterus and cervix in normally mated and supervulated rabbits.
The protein compositions of luminal fluids and mucosal tissue extracts of the rabbit uterus and cervix were investigated with the aid of horizontal polyacrylamide slab-gel electrophoresis, as a part of a study on the preimplantation loss of eggs in the rabbit. The daily samples were obtained from normally mated and superovulated does up to the 6th day of pregnancy. Protein profiles in the uterus and cervix changed almost synchro-nously. Some protein fractions which were absent in blood serum were detected in the uterine and cervical fluids, and a few of them were present also in their tissue extracts. Based on a quantitative fluctuation of uteroglobin as an indicator, daily changes in protein patterns of the secreta of both organs in superovulated does were apparently ad-vanced by 3 days compared with those in normally mated does, and accumulated-uterine-fluid flow descended through the cervical canal from at least 3-4 days after normal mat-ing or just before mating in the superovulated does. The results of these studies suggest that the asynchronously advanced changes in the protein composition of uterine fluid of supervulated does, relative to embryo development, may be one of the causes for high embryonic mortality.