RESUMO
In the bovine oviduct, monosaccharides may play a role in the preparation of gametes for fertilization. Sperm are sequestered in the isthmic region of the oviduct where capacitation, requisite biochemical changes in sperm membranes, may take place. Retention of spermatozoa in the oviductal isthmus is dependent on a carbohydrate recognition system between oviductal epithelium and sperm membrane lectins. The monosaccharide, fucose, has been found to be important to this recognition system. However, both gametes and epithelium are also bathed in oviductal fluid (ODF), and fucose or other monosaccharides may be constituents of ODF and so may be important to sperm binding to oviductal epithelium and subsequent preparation for fertilization. In this study, ODF from dairy cows was analyzed by HPLC for the presence of 5 monosaccharides (fucose, galactose, glucosamine, mannose and xylose). Both whole ODF, collected by cannulation of the entire oviduct of 1 cow over a complete estrous cycle, and regional staged ODF, collected and pooled from 13 cows from the isthmic region only at estrus, were analyzed. We report negligible concentrations of all 5 monosaccharides in both types of ODF analyzed. Because the detection limit of our assay was 10(8) times lower than fucose concentrations found to be physiologically important in earlier in vitro studies, we conclude that bovine ODF does not contain physiologically active levels of free fucose or other, similar monosaccharides at any time of the estrous cycle.
