Development of mast cells is not affected in VAMP-8–deficient mice. (A) VAMP-8 expression levels in tissue homogenates of brain, kidney, murine MCP-5 mast cells, and VAMP-8–deficient and WT BMMCs using anti–VAMP-8. Blots were stripped and reprobed with antiactin. (B) Representative toluidine blue staining of ear and tongue cross-sections (top panel) showing the distribution of tissue mast cells (arrowheads) in VAMP-8–deficient and WT mice (40× objective). (Bottom panel) Corresponding quantitative enumeration of mast cells in ear, tongue, and abdominal skin sections (3 mice/genotype). Data are means plus or minus SEM derived from 5 high-power fields counted/mouse. No significant difference among VAMP-8–deficient and WT mice was observed. (C) Representative toluidine blue staining (top panel) and ultrastructural analysis (bottom panel) by electron microscopy (original magnification ×13 500) of mouse peritoneal mast cells from VAMP-8–deficient and WT mice. (D) Expression of FcϵRI and c-kit on BMMCs from VAMP-8–deficient and WT mice. Continuous and dotted lines represent VAMP-8–deficient and WT BMMCs, respectively, compared with isotype control (dark area).