The cellular specificity of lectin binding in the kidney. II. A light microscopical study in the rabbit.

In order to estimate the usefulness of lectins in the study of the functional segmentation of the nephron, the sites of binding of four lectins were identified in the rabbit kidney. Lectin-peroxidase conjugates were applied to unfixed cryostat sections. The bound conjugates were stained with 3,3'-diaminobenzidine for light microscopical observation. Each lectin has a specific binding pattern along the nephron. The patterns generally fit in with the segmentation of the nephron established by conventional histology. However, in the proximal tubule and in the thick ascending limb the lectin binding suggests functional transitions in histologically homogeneous tubular portions. In contrast to the other cell types of the connecting tubule and of the collecting duct the intercalated cells bind two lectins at their luminal membrane. Segmental differences in the lectin affinity of the basement membrane suggest that this structure has not only mechanical functions. The binding of lectins to luminal membranes in some segments indicate the possibility to use lectins for the separation of particular cell types and for modification of the transport properties of their membranes.