CONTRACTION AND MYOFIBROBLASTS IN RESTORED SKIN

Myofibroblasts and the contraction of split skin-graft donor sites wer e studied in 18 patients. For each patient five samples were studied, taken on days 0, 14, 21, 28, and 35. On each occasion the extensions a nd densities of myofibroblasts were calculated. After the initial meas urement, the subsequent extensions were expressed in percentages of th e first, resulting in mean measurements of 100, 95, 97, 99, and 99%, r espectively. The myofibroblasts in 10 dermic fields were counted under light microscopy at a magnification of 1000 marked with anti-a-smooth muscle actin antibodies using immunoperoxidase, resulting in the mean s of 0.2, 3.8, 1.3, 1.3, and 0.4, respectively. The contraction and th e increase in density of myofibroblasts were transitory and significan t in the samples measured on day 14, but in sample 35 neither of the v ariables was significantly different from the initial sample. These va riables evolved concurrently, corroborating the hypothesis that myofib roblasts are responsible for the contraction.