Histochemical analysis of rat testicular glycoconjugates. 2. β-galactosyl residues in O- and N-linked glycans in seminiferous tubules

Rat testes have been examined with a panel of lectins that bind specifically to oligosaccharide sequences having terminal or subterminal β-galactosyl residues in O-linked glycans, or in the outer chains of complex N-linked glycans:Arachis hypogaea (peanut, AHA), Erythrina cristagalli (coral tree, ECA), Ricinus communis (castor bean, RCA120) and Abrus precatorius (jequirity bean, APA) agglutinins. Pretreatment of sections with neuraminidase, β-galactosidase and removal of alkali-labile O-linked sequences by β-elimination allowed the structure of these glycans to be further explored. In spermatogonia and spermatocytes there was little evidence of glycans terminating in β-galactosyl residues, although these were present at non-reducing terminals as sialylgalactosides. The acrosome contained two subsets of O-linked glycans terminating in sialylgalactosides, while the nuclear cap showed at least two subsets of N-linked sialylgalactosyl as well as O-linked glycans. Spermatozoa exhibited minor changes in the pattern of glycosylation, although the overall pattern of β-galactosyl expression was similar. Binding to Sertoli cells showed the presence of some unsubstituted β-galactosyl terminals on O-linked glycans but few such N-linked residues, while terminal β-galactosides were scanty in tubular basement membranes. © 1992 Chapman & Hall.