Redistribution of aquaporins in uterine epithelial cells at the time of implantation in the rat.

The aim of this study was to investigate the presence of aquaporins 1, 4 and 5 in uterine epithelial cells during the early stages of pregnancy in the rat. Immunofluorescent and immunogold techniques showed that there was a shift of aquaporin 5 to the apical surface of uterine epithelial cells in the mesometrial pole of the uterus at the time of implantation. This study also revealed the absence of aquaporin 4 in the rat uterus during early pregnancy. Aquaporin 1 was observed in stromal blood vessels but there was no change in uterine epithelial cells during early pregnancy. These results suggest that aquaporin 5 plays an important role in the removal of uterine luminal fluid at the time of implantation in the rat and may contribute to the antimesometrial positioning of the implanting blastocyst.