Human wound repair. II. Inflammatory cells, epithelial-mesenchymal interrelations, and fibrogenesis.

Connective tissue repair was studied in a series of skin wounds in young adult males. The tissues were examined at 3, 12, and 24 hr, and at 2, 3, 5, 7, 14, and 21 days after wounding. The neutrophilic leukocytes contain within membrane-bounded vacuoles some fibrin and serum protein from the wound; however, most of the granulocytes lyse and release their cytoplasmic contents into the extracellular space. The mononuclear cells undergo a series of morphologic alterations during which they develop a modest amount of relatively poorly developed rough endoplasmic reticulum and an extensive system of smooth-surfaced membranes prior to active phagocytosis. They could be clearly distinguished from immature fibroblasts by the differences in the development of their organelles, particularly the rough endoplasmic reticulum. The perivascular connective tissue adjacent to the wound contains cells which appear like poorly developed or immature fibroblasts. The development of these cells into mature fibroblasts can be followed during the different stages of wound repair. Intimate contact was observed between basal cells of the regenerated epidermis and monocytes in the wound below: cytoplasmic projections of the basal cells extended beneath the basement lamina to the surface of the monocytes. Such contacts were seen only on the 4th-7th day after wounding. Their possible significance is discussed.