Mast cell numbers in incisional wounds in rat skin as a function of distance, time and treatment.

The dynamic changes in skin mast cell (MC) numbers around incised wounds were studied, using experimental designs amenable to multiple analyses of variance. Sixty-four Wistar albino rats were shaved in the interscapular region, wounded or not wounded, and then killed 2 or 10 days later. During this period, the rats were exposed continually to a cold (2 degrees C) or control (20 degrees C) climate and treated daily over the shaved region with either tap water or a weak sulphuric acid (pH 3.5) solution. The MCs within five adjacent fields of the wound or the control reference and within the superficial and deep halves of the skin were counted (at x 400). The greatest decrease in MC numbers occurred within about 700 microns of the wound. Whereas the paucity of MCs within the wound region was evident at 2 days, near-normal levels were achieved by day 10. Cold exposure produced little effect, but MCs responded differently to the water and acid treatments as a function of distance and skin depth.