The ‘transitional’ mucosa adjacent to large bowel carcinoma—electron microscopic features and myofibroblast reaction

An electron microscopic study of the 'transitional' mucosa adjacent to 10 carcinomas of the colon showed impaired maturation of epithelial cells. The pericryptal fibroblast layer was absent, accounting for an increase in the length and distension of crypts. In the tunica propria a massive accumulation of myofibroblasts was noted and was indicative of an intensive fibre-producing activity. Review of the literature identifies various theories concerning the functions of myofibroblasts in respect of contraction, embryonal collagen-fibre formation and non-specific stromal reaction. Of these, the latter two are considered likely in relationship to transitional colonic mucosa.