Fig. 3. Photomicrographs of toluidine blue and eosin staining of mast cells in the dermis of hind paw skin at 4 weeks postfracture. (A ) Dermal mast cells are intact in control rats, showing a dark blue staining, whereas degranulating mast cells appearing purple-red are observed 4 weeks postfracture (B and C ). The degranulation can be divided into two types: slight discharge of granules (B ) and extensive disruption and discharge of granules (C ). The number of mast cells (D ) and the percentage of degranulated mast cells (E ) were dramatically increased in the dermis at 4 weeks postfracture (n = 6 per cohort). **P < 0.01, compared with control animals. Fx = fracture; MCs = mast cells.