[Myofibroblasts in desmoids]

Ten desmoids are examined electron-microscopically and by the fluorescent antibody method. The cells with the ultrastructural signs of myofibroblasts are found in tumours. Immunomorphologically these cells were found to contain cytoplasmic myosin occurring in the cells of both muscular and non-muscular origin. The structural myosin of smooth muscle cells was not detected in these elements. The above cells are considered to be the modification of fibroblasts which have no relation to the smooth muscle cells. Non-homogeneity of myofibroblast population is noted.