FIG. 2.

Mc-cpa^−/− mast cells are normal with regard to staining for c-Kit and FcɛRI expression, acridine orange staining, and transmission electron microscopy. Peritoneal mast cells from Mc-cpa^+/+ (+/+) (A, C, and E) and Mc-cpa^−/− (−/−) (B, D, and F) mice were analyzed by flow cytometry for c-Kit and FcɛRI expression (A and B) (for relative and absolute mast cell frequencies, see Table 1), by acridine orange staining showing acidic granules (C and D), and by electron microscopy to reveal their ultrastructure (E and F). The scale bars in panel D (12 μm) and panel F (8.5 μm) apply to panels C and D and panels E and F, respectively.