3Professor of Anatomy, Department of Anatomy, Mashhad University of Medical Sciences and Health Services, Mashhad, Iran
Previous studies have shown that epididymal epithelium and its secretions are critical for sperm maturation. These secretions contain many glycoconjugates with sialic acid terminal sugar. This terminal sugar by interveining in cellular interactions and masking surface receptors, has an important role in sperm maturation and protection. Moreover lectins have been employed as useful probes to detect the presence of glycoconjugates with specific sugar residues such as sialic acid. Considering the importance of sialic acid, distribution of this terminal sugar in different parts of mouse epididymis was studied by means of lectin histochemistry. For this purpose, epididymal tissue species were obtained from 15 adult male BALB/c mice. After fixation and routine laboratory process, 5 µm sections prepared from paraffin blocks. Slides were exposed to lectins with lectin-histochemistry. For this purpose, Wheat germ agglutinin (WGA), specific for sialic acid, was employed. Then they assessed with light microscope. The rate of reactions in epithelial cells and spermatozoa were significantly different n different parts of epididyms. In this manner that, in spermatozoa, stereo cilia and luminal surface the least reactions were seen in caput, while the most reactions were seen in cauda. Epithelial cells, too, showed less reaction in caput comparing to corpus and tail of epididymis. Sialic acid has been identified in many glycoproteins secreted by epididymis and is necessary for sperm maturation. It seems that this maturation happens mostly in body and tail of epididymis during epididymal transit. Increase in sialic acid content of spermatozoa during epididymal transit is probably due to the secretion of glycoconjugates containing this component by epididymal principal and flask cells.