Myofibroblasts, cells with intermediate features between smooth muscle cells and
fibroblasts, have been described as an important cellular component of schistosomal portal
fibrosis. The origin, distribution and fate of myofibroblasts were investigated by means of
light, fluorescent, immunoenzymatic and ultrastructural techniques in wedge liver biopsies
from 68 patients with the hepatosplenic form of schistosomiasis. Results demonstrated that the
presence of myofibroblasts varied considerably from case to case and was always related to
smooth muscle cell dispersion, which occurred around medium-sized damaged portal vein
branches. By sequential observation of several cases, it was evident that myofibroblasts
derived by differentiation of vascular smooth muscle and gradually tended to disappear, some
of them further differentiating into fibroblasts. Thus, in schistosomal pipestem fibrosis
myofibroblasts appear as transient cells, focally accumulated around damaged portal vein
branches, and do not seem to have by themselves any important participation in the
pathogenesis of hepatosplenic schistosomiasis.
