[Roles of myofibroblasts in the stroma of human gastric carcinoma].

The stromal reaction of human gastric carcinoma was studied about myofibroblast proliferation and collagen type I, III synthesis in 28 surgical materials (15 cases of well differentiated type, 13 cases of poorly differentiated type), using immunohistochemical and immunoelectron microscopical techniques. Immunohistochemically, myofibroblasts showed marked reactivity to both anti-alpha smooth muscle actin (alpha SM-1) MAb and anti-vimentin MAb, and they were broadly distributed in the stroma of gastric carcinomas. Moreover, myofibroblasts revealed their own characteristics surrounding collagenous fibers under electron microscope. The myofibroblast proliferation was more prominent in poorly differentiated carcinoma and invasive carcinomas. On the other hand, much more myofibroblasts were observed in the marginal portion of cancer nests than the central area. The distribution of collagen type III was very similar to that of myofibroblast. These findings suggest that the proliferation of myofibroblast and collagen synthesis in tumor stroma were obvious host response against carcinomas, and this phenomenon may reveal an important biological status in gastric carcinoma.