Transforming growth factor type e is a potent mitogen for epithelial and fibroblastic cells in vitro. It is primarily produced by epithelial tissues and cells, including normal skin keratinocytes. In this study we examined the effects of transforming growth factor type e in vivo and in vitro. On application of transforming growth factor type e to the chorioallantoic membrane of 8-day-old chick embryos, we noted a prominent thickening of the membrane caused primarily by fibroblastic and epithelial proliferation. In a subsequent study, transforming growth factor type e suspended in Matrigel was injected subcutaneously into the abdominal wall of Swiss National Institutes of Health mice. Significant influx of first neutrophils and then macrophages into the gel of transforming growth factor type e-treated mice, but not of control mice, was observed. Transforming growth factor type e also exhibited a potent chemoattractive effect on the J774 macrophage cell line in vitro. In transcutaneous mouse wounds, topical administration of transforming growth factor type e led first to an influx of neutrophils and macrophages, followed by an increased formation of granulation tissue in the transforming growth factor type e-treated wounds. These results suggest that transforming growth factor type e plays an important role in wound healing as a chemoattractant for neutrophils and macrophages and as a mitogen for epithelial and fibroblastic cells.