Fucosylated Oligosaccharide Antigen Expression In The Epididymis

Mammalian spermatozoa are not mature when they leave the testis, their development continues during their passage through the epididymis. Epididymis secrets glycoproteins into the luminal fluid, and creates a microenvironment of the epididymis, which is necessary for spermatozoa maturation, acquiring forward motility and fertility potential. Lately, it is found that in human seminal plasma there have very high concentration free oligosaccharides (0.3-0.4mg/ml) which is rich in fucose carried LeX and LeY epitopes and assumed that free oligosaccharides may be involved in increasing sperm longevity, modifying sperm motion, promoting sperm binding to eggs in oviduct and increasing immunosuppressive activity of sperm. But the source, distribution and function of the fucosylated oligosaccharides are still unclear. This study mainly used LeX and LeY antibodies as a probe to identify the expression and distribution of the two antigens in epididymis by immunohistochemistry, Dot-blot, RT-PCR and immunofluorescence analysis. The results revealed that in mouse and human LeX and LeY were negative in the testis, but dramatically turned to strong expression in the caput epididymisl, where they coated sperm surface. But the antigens showed light positive or negative in caput and cauda. The FUT gene, which is the key enzyme to catalyze the synthesis of LeX and LeY, presented in all region of the epididymis, but the products of FUT gene, LeX and LeY, were in different degree. They may be absorbed by some cells or be decomposed by glycosidase. It was indicated that LeX and LeY in seminal plasma may come from epididymis. The expressions of the two antigens in rat and dog were different from those in mouse and human. The results can be presumed that the two antigens expressions were obvious differences in different species. Further investigation will be required to speculate the biological significance of fucosylated oligosaccharides in male reproduction.