Human large intestinal epithelium: light microscopy, histochemistry, and ultrastructure

Area of Science:

• Gastroenterology
• Cell Biology
• Histology

Background:

• Limited data exists on normal large intestinal epithelium morphology, hindering accurate diagnosis of abnormalities.
• Previous studies focused mainly on the rectum, neglecting other segments.

Purpose of the Study:

• To comprehensively characterize the morphologic and histochemical features of normal large intestinal epithelium across different segments.
• To establish a baseline for differentiating normal from abnormal epithelial cells.

Main Methods:

• Analysis of large intestinal epithelium from 41 individuals using light microscopy, histochemistry, and electron microscopy (transmission and scanning).
• Samples were collected from ascending, transverse, descending, and rectosigmoid regions.

Main Results:

• Significant regional variations in morphology and histochemistry were observed.
• Three primary cell phenotypes identified: undifferentiated, mucous, and endocrine cells.
• Rectal epithelium showed a higher concentration of endocrine cells and predominantly acidic mucin, unlike the ascending colon's neutral mucopolysaccharide.

Conclusions:

• Normal large intestinal epithelium exhibits distinct regional characteristics.
• Observed ultrastructural features in abnormal epithelium may be artifacts due to lack of region-specific normal controls.
• Future studies on abnormal epithelium require comparison with normal epithelium from the identical intestinal segment.