Glycomolecule modifications in the seminiferous epithelial cells and in the acrosome of post-testicular spermatozoa in the alpaca

Abstract

A lectin histochemical investigation of the seminiferous epithelium and acrosomes of spermatozoa present in the efferent ductules and epididymal regions was carried out in the alpaca. The histochemical characterization was performed using a battery of different lectins: Con-A, UEA-I, LTA, WGA, GSA-IB4, SBA, PNA, ECA, DBA, MAL-II and SNA. Sialidase digestion and deglycosilation pre-treatments were also employed. The cytoplasm of the Sertoli cells contained N-linked oligosaccharides with α-D-Man/α-D-Glc and GlcNAc and O-linked glycans with α-L-Fuc, β-GalNAc, β-D-Gal-(1-4)-D-GlcNAc, α-Gal and Neu5Acα2,6α-GalNAc moieties whereas β-D-Gal-(1-3)-D-GalNAc residues were included in both O- and N-glycoproteins. Spermatogonia expressed α-D-Man/α-D-Glc residues included in N-glycoproteins and α-Fuc in O-glycoproteins. Spermatocytes contained the N-glycoproteins residues α-D-Man/α-D-Glc and GlcNAc and the O-glycoproteins residues α-L-Fuc, β-D-Gal-(1-4)-D-GlcNAc, α-Gal, β-GalNAc, Neu5Acα2,6α-GalNAc and Neu5Acα2,6β-D-Gal-(1-3)-D-GalNAc. The results of the present study show differences in the presence and distribution of lectin reactive sites throughout the acrosomal development in the alpaca. In particular, Fuc moieties were found only during the Golgi-phase of spermatids, α-Gal were found in the acrosome of Golgi- and cap-phase spermatids, sialic-acid/α-GalNAc sequence was revealed during the cap-phase and elongated spermatids, and α-D-Man/α-D-Glc and GlcNAc were detected only in the acrosomes of elongated spermatids. Finally, β-GalNAc, β-D-Gal-(1-3)-D-GalNAc and β-D-Gal-(1-4)-D-GlcNAc were added to acrosomal glycoproteins in the early stages of spermatogenesis and remained unchanged during the later phases. Differences in the carbohydrate expression were also demonstrated on the sperm acrosomes during passage through the post-testicular ducts.