CHANGES IN LECTIN-BINDING SITES DURING EARLY HUMAN LIVER DEVELOPMENT

In this study we investigated whether changes in glycosylation during liver morphogenesis correlate with the early development of individual structures in the human liver. Therefore, we localized the binding of the lectins from Sambucus nigra (SNA; specific for sialic acid), Trit icum vulgare (WGA; specific for N-acetylglucosamine and sialic acid), Ricinus communis (RCA I; specific for beta-galactose), Lotus tetragono lobus (LTA; specific for alpha-fucose) and Concanavalia ensiformis (Co n A; specific for alpha-mannose) in the human liver between the 4th an d the 12th gestational week (GW). Cell membranes of early hepatocytes (5th-6th GW) showed strong staining for RCA I, which decreased noticea bly from the 8th-9th GW onward. Early intrahepatic capillaries (4th-5t h GW) showed reactions only for WGA and RCA I. Reactions for SNA occur red later (6th-9th GW). At this time a fine granular staining for SNA was visible at the sinusoidal sides of hepatocytes. The hepatocytes of the outer limiting plate were specifically stained by WGA, Con A, and SNA in the 9th GW and the staining remained visible in developing bil e ducts up to the 12th GW. The possible biological significance of the appearance or disappearance of carbohydrate moieties during early hum an liver development is discussed.