Ultrastructural Localization of Blood Group Antigen a and Cell Coat on Human Buccal Epithelial Cells

The ultrastructural localization of blood group substance A and its relationship to the cell coat was studied on exfoliated buccal epithelial cells from four male subjects. The antigens were detected by a double layer immunoperoxidase staining method (IP) as well as a double layer immunoferritin (IF) staining method. The cell coat was studied using ruthenium red. There was no variation in results obtained by the IP and IF staining procedures. Positive reacting cells (IP and IF staining) showed either an even or a patchy distribution of the reaction products along the outer part of the cell membrane. Some cells had only very little or no reaction products. The cell coat appeared as an evenly distributed electron dense granular layer at a localization corresponding to that of the antigen.