Ultrastructural evidence for the presence of "fibroclasts" and "myofibroclasts" in wound healing tissues.

We have observed, by light and electron microscopy, fibroblast-like cells which appear to be involved in collagen fiber and filament degradation. These cells are most prominent in the dermis of mature hypertrophic scars which were clinically observed to be in the remodeling phase of wound repair. Total incorporation of collagen filaments within cellular vacuoles, as seen by TEM, appears to precede the enzymatic degradation of the collagen. Cytoplasmic contractile bundles and/or collagen filament remnants found within residual lysosomes were also seen in many of these cells. Evidence of structural reorganization within the tissue was observed by means of SEM. These cells appear to be similar to osteoclasts in function: thus we propose to name them "fibroclasts" and "myofibroclasts."