[Electron microscopy of colonic polyps. I. Comparative study of epithelial cells from adenomatous and adenopapillary polyps].

Ultrastructural characteristics of premalignant epithelial dysplasia were studied electronmicroscopically by comparing epithelial cells of adenomatous- and adenopapillary polyps. In adenomatous polyps the rate of absorptive and goblet cells, their electron microscopic appearance did not differ from those of the normal colonic mucosa. In dysplastic areas of adenopapillary polyps severe proliferation of undifferentiated epithelial cells and disturbance of the maturation of absorptive and goblet cells was found. Severe damage to the cell membrane, atypical vacuola and dense bodies in the apical areas of absorptive cells were also seen. An abundance of Leuchtenberger's inclusion bodies as an important sign of the malignant transformation have occurred.