Electron-microscopic study of the villous adenoma of the colon

Ulcerative colitis: electron microscopic studies with special reference to development of crypt abscesses

Electron microscopy of the colonic mucosa was performed in 33 patients with acute ulcerative colitis. The process of the development of crypt abscesses was studied. Inflammatory cells migrated intercellularly from the lamina propria and did not destruct the neighboring epithelial cells. Abnormal maturation of the epithelial cells was observed. Loose connection and separation of immature epithelial cells may promote migration of inflammatory cells.

Basal lamina fenestrations in the human colon: transmission and scanning electron microscope study

Basal lamina at the interface between colonic epithelial cells and the lamina propria was exposed by incubating colonic specimens in 1% boric acid solutions. Examination of this epithelial-stromal interface by scanning electron microscopy (SEM) showed a smooth, slightly undulating basal lamina covering crypts and luminal surfaces. The basal lamina on the luminal surfaces had numerous round or ovoid fenestrations, most measuring 2.5-4.0 microns. These were continuous with channels in the collagen fiber network of the lamina propria. Except very near the surface, no fenestrations were found in the basal lamina lining the crypts. Transmission electron microscopy (TEM) of serial thin sections of colonic mucosa without the epithelial cells removed showed only a few actual basal lamina fenestrations. Rarely, epithelial cell processes extended into the lamina propria through the basal lamina. Most of the fenestrations seen by SEM appeared to correspond spatially by TEM to foci of close contact between the basal lamina and underlying fibroblastic cell processes. At these sites the basal lamina and fibroblastic cell process might be removed along with the overlying epithelial cells during processing with boric acid. These data support functional differences in epithelial-stromal interaction between cell populations lining the luminal surface and those making up the crypt lining and pericryptal fibroblast sheath. The TEM findings demonstrate that the human colonic basal lamina is not absolutely continuous and that the development of basal lamina fenestrations and epithelial cell processes extending into the lamina propria is not pathognomonic of neoplastic transformation and stromal invasion.

Electron microscopic study of adenocarcinoma of the small bowel associated with Crohn's disease

"Crohn's Carcinoma" of a 34-year-old patient is presented in this paper. The fine structure of the tumour is discussed in detail, because there have been no previous reports of electron microscopic studies of this tumour. The adenocarcinoma cells were electron microscopically less differentiated than expected on the basis of light microscopic examinations. In the tumor cells, several round dense granules were observed. Similar granules were also described in the cells of intestinal type gastric and colon cancers, being considered a sign of pathologic mucus secretion. In a part of the tumour cells, intracisternal parallel tubular inclusions were seen like those described in malignant melanoma and osteosarcoma. In the dysplastic small-bowel mucosa adjacent to the tumour, the maturation disorder of the epithelial cells was similar to changes described in the precancerous states of the colon.

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.

Electron microscopy of polyps of the colon. I. Comparative study of the epithelial cells of adenomatous and adenopapillary polyps

By comparing the electron-microscopic pictures of adenomatous and adenopapillary polyps, the ultrastructural characteristics of premalignant epithelial dysplasia were studied. In highly differentiated adenomatous polyps, the ratio and the electron-microscopic appearance of absorptive and goblet cells did not differ from the epithelial cells of the normal mucosa of the colon. In the dysplastic regions of adenopapillary polyps, the intensive proliferation in several layers of undifferentiated epithelial cells, and the maturation disorder of absorptive and goblet cells, were observed. Severe changes occurred on the cell membrane as well as atypical vacuoles and dense bodies in the apical regions of the cell membrane. Several inclusion bodies of Leuchtenberger were observed, these being considered an important characteristic of malignant transformation.

Electron microscopy of polyps of the colon. II. Inclusion bodies of Leuchtenberger

The electron-microscopic characteristics of the LEUCHTENBERGER'S inclusion bodies were studied in adenomatous, papillary and adeno-papillary polyps of the colon. According to them, formation of intracellular inclusions is due to focal cytoplasmic degradation, and that of intercellular inclusions to the herniation of the cytoplasmic part of epithelial cells. The formation of inclusions is believed to be connected with the low stage of development of the plasma membrane of rapidly proliferating undifferentiated colonic epithelial cells. During malignant transformation of polyps, the frequently occurring inclusions are considered an important morphological sign.

Electron microscopic study of carcinoma of the colon

During electron microscopic studies of 24 carcinomas of the colon the authors compared the ultrastructural characteristics of tumorous epithelial cells of various degrees of differentiation. Beside the epithelial elements, the myofibroblast reaction, considered to be a local immune reaction due to invasive tumour cells, observable in the stroma of tumours was also treated in detail. It was observed that myofibroblasts develop from the fibroblasts of the matrix of colonic mucosa.