Contractile events during inflammation.

Contractile events during wound healing. During granulation tissue contraction, fibroblasts develop characteristics typical of smooth muscle; (1) they contain an extensive cytoplasmic fibrillar system, (2) they show immunofluorescent labeling of anti-actin antibodies, (3) there are cell and cell to stroma attachments, (4) strips of granulation tissue, when tested pharmacologically in vitro, behave similarly to smooth muscle. These data support the view that under certain conditions, fibroblasts can differentiate into a cell type structurally and functionally similar to smooth muscle and this cell, the 'myofibroblast', plays an important role in connective tissue contraction. During epithelialization, epidermal cells develop an extensive cytoplasmic contractile apparatus which has morphological and immunological characteristics similar to those of myofibroblasts. Such apparatus disappears as soon as epithelialization is completed. It is proposed that such a contractile apparatus plays a role in cell motility enabeling individual cells to rearrange themselves in an appropriate pattern. In conclusion, significant amounts of contractile proteins may be synthetized by fibroblasts and epithelial cells during wound healing and may play an important role in this process.