Figure 2.

Schematic illustration showing the evolution of the (myo)fibroblast phenotype.

Notes: The myofibroblastic modulation of fibroblastic cells begins with the appearance of the proto myofibroblast, whose stress fibers contain only β- and γ-cytoplasmic actins and evolves, but not necessarily always, into the appearance of the differentiated myofibroblast, the most common variant of this cell, with stress fibers containing α-smooth muscle actin. Soluble factors, extracellular matrix components, and/or the mechanical microenvironment are involved in myofibroblastic differentiation. The myofibroblast can disappear by apoptosis; while deactivation leading to a quiescent phenotype has not been clearly demonstrated, at least in vivo.