Lectins are glycoproteins of a non-immune origin often used as histochemical reagents to study the distribution of glycoconjugates in different types of tissues. In this study, we performed a comparative cellular localization of sugar residues in bull and donkey testes using immunofluorescent lectin histochemistry. We inspected the cellular localization of the glycoconjugates within the testes using 11 biotin-labeled lectins (LCA, ConA, PNA, WGA, DBA, SBA, ECA, BPL, PTL-II, UEA-1, and PHA-E4) classified under six groups. Although the basic testicular structure in both species was similar, the cellular components showed different lectin localization patterns. The statistical analysis revealed no significant association between the intensity of labeling and different variables, including group and type of lectin and type of cell examined, at p < 0.05. However, a stronger response tended to occur in the donkey than in the bull testes (odds ratio: 1.3). These findings may be associated with the different cellular compositions of the glycoproteins and modification changes during spermatogenesis. Moreover, glycoconjugate profiling through lectin histochemistry can characterize some cell-type selective markers that will be helpful in studying bull and donkey spermatogenesis.

The lectin binding characteristics of mouse placental cells were examined. Wax embedded tissue sections of placentae from d 14 pregnant mice were stained with 26 lectins, with a wide range of sugar specificities. Cell cultures prepared from d 14 mouse placentae and cultured for 24 h were stained with 7 of the lectins to determine if they could be used as markers for the different trophoblast cells in culture. In tissue sections all placental cell populations bound lectin but no lectin bound specifically to any single trophoblast population. All the lectins which bound to layer 1 cytotrophoblast lining the maternal blood spaces of the labyrinthine placenta also bound to the fetal endothelium of the labyrinthine placenta. Binding of lectin appeared strongest on the adluminal membrane of these cell populations suggesting a role for the carbohydrate moieties in nutrient transfer. Few lectins bound to junctional zone trophoblast. Overall, the binding of lectin to cultured cells did not correlate exactly with lectin binding to the cell populations in tissue sections. The value of lectins as markers for placental cells in culture was therefore found to be limited. Our findings indicate that carbohydrate expression by at least some placental cells may vary in culture from that expressed by the cells in vivo with obvious concerns for the validity of functional in vitro studies.

Mucous and oxynticopeptic cells in the gastric mucosa of the seps, Chalcides chalcides (Linnaeus, 1758) were examined by standard histochemical staining methods and by lectin histochemistry. The epithelial mucous cells lining the surface of the stomach and the mucous cells of the fundic glands elaborated mainly neutral glycoproteins with β(1,4)GlcNAc oligomers, GalNAc glycosidic residues and Galβ1,3GalNAc terminal sequences. The mucous cells of the fundic glands were stained specifically with the Paradoxical Con A method. The mucosecreting cells of the pyloric glands produced neutral glycoproteins, with β(1,4)GlcNAc oligomers, GalNAc residues and Galβ1,3GalNAc terminal sequences. Terminal L-fucose bound to the penultimate GlcNAc residues, and/or difucosylated oligosaccharides were also present. The pyloric glands did not stain with the Paradoxical Con A procedure. The morphology of the oxynticopeptic cells changes from the oral to the aboral region of the fundic mucosa. In the oral fundic tract the oxynticopeptic cells showed cytoplasm filled with zymogen granules, while in the aboral fundic region these cells contained few zymogen granules and showed cytoplasm full of empty vesicles, typical of the acid secreting cells. A secretion gradient of proteolytic enzymes and hydrochloric acid along the fundic mucosa of the seps can be hypothesised.