Granulation tissue fibroblasts (myofibroblasts) develop several ultrastructural and
biochemical features of smooth muscle (SM) cells, including the presence of microfilaments
bundles and the expression of α-SM actin, the actin isoform typical of contractile vascular SM
cells. Myofibroblasts have been suggested to play a role in wound contraction and in
retractile phenomena observed during fibrotic diseases. When granulation tissue evolves
into a scar, myofibroblasts containing α-SM actin disappear, probably as a result of …