Presence of mast cells in various oral mucosal sites in juvenile and adult rats

Abstract

The present investigation was designed to study the number of mast cells in various oral mucosal sites in juvenile and adult rats, with special reference to presence of subtypes of mast cells. Fifteen juvenile (1-month-old) and 15 adult (6-month-old) rats were used. Biopsies were taken from tongue, bucca, marginal gingiva (incisor area), and intestine (jejunum). For optimal preservation of the stainability of subtypes of mast cells, a fixative with low aldehyde concentration and low pH was used. The biopsies were embedded in paraffin-wax. The first of three consecutive sections (5 mu) was stained in toluidine blue for 30 s, the second in toluidine blue for 7 days, and the third in astra blue/safranine. The total number of mast cells was represented by all cells positive to toluidine blue after 7 days' staining, or the sum of cells positive to astra blue and safranine. Cells positive to toluidine blue after 30 s were classified as connective tissue mast cells (CTMCs), and those positive after 7 days, but not after 30 s, as mucosal mast cells (MMCs). Cells positive to safranine in the astra blue/safranine staining sequence were classified as CTMCs, and those positive to astra blue as MMCs. Cells with intermediate staining characteristics in the astra blue/safranine staining sequence were recorded separately. The total number of mast cells in the tongue, buccal mucosa, and gingival mucosa was significantly higher in the juvenile than in the adult rats. In the buccal and gingival mucosa, more than twice as many mast cells were found in the young animals.(ABSTRACT TRUNCATED AT 250 WORDS)