FIGURE 3.

Histochemistry of the peritoneal MCs in WT and Prss31-null B6 mice. A and B, peritoneal lavage was performed on WT (A) and Prss31-null (B) B6 mice. Cytospins of the cells in the resulting exudates were stained with toluidine blue or with Alcian blue followed by safranin. Shown at lower power (highlighted by black arrows) and at higher power in the bottom left insets are the safranin⁺ MCs in the exudates. Shown at higher power in the bottom right insets are the corresponding peritoneal MCs in these exudates stained with toluidine blue. Toluidine blue recognizes all types of negatively charged serglycin proteoglycans in the granules of MCs, including those that contain chondroitin sulfate diB, chondroitin sulfate E, and heparin glycosaminoglycans. In contrast, safranin preferentially recognizes those serglycin proteoglycans that contain heparin glycosaminoglycans. The relative numbers of safranin⁺ and toluidine blue⁺ MCs in the peritoneal cavities of the two mouse strains were the same, as were their degree of granulation and expression of heparin-containing serglycin proteoglycans.