title: Formalin sensitivity and differential staining of mast cells in human dermis.
abstract: The characteristics of the human dermal mast cell population with respect to formalin fixation sensitivity, toluidine blue staining and alcian blue/safranin staining were studied. Thirty-seven specimens of normal human skin were bisected. One half was fixed in 10% neutral buffered formalin and the other in Carnoy's fixative. Sections were cut and stained with either toluidine blue or alcian blue/safranin. Significantly more mast cells were visualized with alcian blue/safranin than with toluidine blue. With both stains, only approximately 50% of the mast cells observed in the Carnoy's fixed tissue could be visualized in the formalin-fixed tissue. Alcian blue/safranin staining revealed three patterns of mast cell granule staining: mast cells containing only alcian blue-positive granules, mast cells containing only safranin-positive granules, and mast cells containing a mixture of alcian blue-positive granules and safranin-positive granules. Mast cells containing only alcian blue-positive granules constituted the majority of the dermal mast cell population and 73% of these mast cells were formalin-sensitive. Mast cells containing only safranin-positive granules and those containing a mixture of alcian blue-positive granules and safranin-positive granules showed no evidence of formalin sensitivity. The human dermal mast cell population, therefore, displays heterogeneity with respect to formalin fixation sensitivity and alcian blue/safranin staining. Dermal mast cells were visualized in significantly greater numbers in skin from the head compared with that from the body or limbs.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005557:Formaldehyde; D006801:Humans; D008297:Male; D008407:Mast Cells / Q000145:classification* / Q000473:pathology; D008875:Middle Aged; D012867:Skin / Q000166:cytology* / Q000473:pathology; D012871:Skin Diseases / Q000473:pathology; D013194:Staining and Labeling
chemical_list: D005557:Formaldehyde