Variations in the staining of cutaneous mast cells

Mast cells of dog skin were examined by staining with Alcian Blue in magnesium chloride solutions and by a periodic acid-Schiff method. The results suggest that the usual fall in cell-count with age is largely due to increasing blockage of staining by protein-saccharide interaction. The degree of sulphation and molecular weight of the saccharide polymer appears to be reduced with age in animals with either normal or diseased skin, but in the diseased animals the protein-polysaccharide interaction did not occur. Significant differences between body regions occur, particularly in the anal region. It is considered unlikely that significant amounts of glycosaminoglycans other than heparin are present in dog mast cells.