Comparison of lung histopathology and density of intact and degranulated mast cells in mice following ischemia-reperfusion injury. Toluidine blue staining is shown for left lungs subjected to ischemia-reperfusion (C-D) and contralateral non-ischemic lungs (A-B) after ischemia-reperfusion injury. Degranulation was detected by the finding of metachromatic cells with indistinct, granulated borders in tissue sections stained with toluidine blue. Examples of parenchymal mast cells are shown by arrows and are enlarged in the insets. Scale bar denotes 100 μm. (E) In random low-power microscopic fields, mean counts of metachromatic toluidine blue-staining cells were compared in lungs subjected to ischemia-reperfusion injury and from contralateral control lungs from KitW-sh/W-sh mice with mastocytosis generated by injection of BMCMC and from untreated wild-type animals (n = 5 per group). The percentage of degranulated mast cells is compared in BMCMC-injected KitW-sh/W-sh mice between ischemia-reperfusion and contralateral non-ischemic lungs (F). **P < 0.01; ***P < 0.001.