Three-dimensional configuration of crypts of different types of colorectal adenomas.

The three-dimensional configuration of isolated crypts of normal human colonic mucosa and colorectal adenomas was examined by scanning electron microscopy. For isolation of the crypts, the digestion method with HC1 was used for formalin fixed tissues, and the separation method with ethylenediaminetetraacetic acid (EDTA) following ultrasonication was applied to fresh tissues. In a comparative study, the NaOH cell-maceration method, which visualized the sub-basal laminal collagen sheath, was applied. The isolated crypts from the normal colon were visualized as a single straight tubule resembling a test tube. Most isolated crypts of the tubular adenomas were visualized as elongated fan-like structures with several protuberances and a few short branchings. Their average length was more than twice that of the normal colonic mucosa crypts. Most crypts of the villous adenomas were visualized as slender tubules without protuberances and short branchings, and their average length was three times that of the tubular adenoma crypts. Most crypts of the tubulovillous adenomas were long and triangular with several longitudinal folds and protuberances, and the average length was about three times that of the tubular adenoma crypts.