Review of the literature shows that numerous authors admit the existence during various inflammatory reactions, and especially in granulation and cicatricial tissues, of peculiar connective tissue cells e.g. modified fibroblast or myofibroblast, with intermediate features between a fibroblast and a smooth muscle cell. Some of the physical and structural characteristics of these tissues would depend on these cells. The ultrastructural features of the cells in human and experimental pathology as well as their connection with the extracellular matrix are recalled.