This study was performed to evaluate the application of different lectins and monoclonal antibodies against ABH antigens to detect and characterize carbohydrate structures in capillaries of skeletal muscle from humans and laboratory animals. Blood group specific lectins (Griffonia simplicifolia, Griffonia simplicifolia isolectin B4, Lotus tetragonolobus, Ulex europaeus, and Dolichos biflorus) and monoclonal antibodies reacting with histo-blood group carbohydrate antigens belonging to type 1 (Le(a)) and type 2 (H, A and Le(y)) chains were used as histological markers for capillaries in sections from skeletal muscle. The material consisted of 20 human masseter muscle biopsies from individuals with known blood types: (eight blood group O, nine blood group A, two blood group B, and one blood group AB) and masseter muscles specimens from different laboratory animals (mouse, rat, rabbit, cat, dog, pig, cow, and macaca monkey). Unfixed sections and an avidin alkaline phosphatase method were used to visualize the specific reaction. Ulex lectin stained capillaries in all human biopsies either strongly or moderately. Strong muscle capillary reaction was observed in biopsies from O, B and AB individuals while capillaries from A individuals were only moderately stained. Griffonia simplicifolia marked capillaries in A, B, and AB individuals and Griffonia simplicifolia isolectin B4 stained capillaries in muscle biopsies from B and AB donors. Dolichos biflorus was a weak marker of muscle capillaries from A individuals. Only capillaries from O individuals were stained with the antibody against H type 2. Capillary reaction was not observed with the other antibodies used. Girffonia simplicifolia was an excellent marker for capillaries in mouse muscle while Griffonia simplicifolia isolectin B4 is recommended for rat muscles.(ABSTRACT TRUNCATED AT 250 WORDS)