Fig. 1. Fluorescence photomicrographs of costaining of mast cells and keratinocytes in hind paw skin 4 weeks postfracture. In skin from control rats only a few mast cells were present in the superficial dermis (A ). The number of detectable mast cells and degranulation were slightly increased in the upper dermis at 4 weeks postcast (B ), while dramatically increased in the upper dermis adjacent to the epidermal basement membrane 4 weeks postfracture (C ). Scale bar = 50 μm. (D ) Quantification of mast cell-positive cells in the upper-middle dermis. ***P < 0.001 for ipsilateral fracture (n = 9 rats) versus  control (n = 5) values, *P < 0.05 for ipsilateral cast (n = 5 rats) versus  control (n = 5) values, ##P < 0.01 for ipsialateral to fracture (n = 5) versus  ipsilateral to cast (n = 5). Fx = fracture.