Evolution of the surface of mouse myocardial cells during ontogenesis. II. Changes of fluorescent lectin-binding sites.

Fluorescein isothiocyanate-conjugated lectins (FTC-lectins) have been used to study the occurrence and the distribution of their receptors in the coating of mouse myocardial cells throughout their differentiation (from 10 days post-coitum to the adult stage). FTC-Con A, -WGA and -PNA specifically inhibited by alpha-mannosyl, beta-N-acetylglucosaminyl and beta-galactosyl residues, respectively, bind to the cell surface whatever the stage of differentiation. FTC-SBA and -HPA, specifically inhibited by alpha-N-acetylgalactosaminyl residues, bind to the coating of adult cells; their receptor sites appear only at day 18 of development. FTC-UeA, specifically inhibited by fucosyl residues also binds to adult cells. In sections of embryonic hearts, FTC-UeA is trapped by a lectin-like component; this UeA binding can be prevented with mannosyl-substituted serum albumin. Isolated embryonic myocardial cells do not bind FTC-UeA. FTC-BS I-A4 and -BS I-B4, specifically inhibited by alpha-N-acetylgalactosaminyl and alpha-galactosyl residues, respectively, bind only to the capillaries of adult heart. These results show that the differentiation of myocardial cells is accompanied by the sequential acquisition of lectin-binding sites. These changes express the maturation of cell coating glycoconjugates.