Studies on the colonization mechanism of indigenous bacteria in alimentary tract

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This research clarified the colonization mechanisms of indigenous bacteria in rat alimentary tracts. The results obtained in this research are as follows:1. Fundamental colonization site of indigenous bacteria is the epithelial cells with late apoptotic stage in intestinal villi and Peyer's patches.2. Differentiation of M cells in the follicle-associated epithelium (FAE) is co-related with the colonization of indigenous bacteria on FAE and neighboring mucosa. The ordinary columnar epithelial cells engulf the degenerated bacteria, whereas M cells engulf the intact bacteria in FAE of Peyer's patches. This engulfment of bacteria might be mediated with membrane receptor in M cells form ultrastructural findings.3. Specific sugar expression was histochemically determined on the epithelial cells with late apoptotic stage, whereas M cells expressed no specific sugar.4. Fundamental colonization site of indigenous bacteria is the epithelial cells with late apoptotic stage in entire alimentary tract. From these sites, indigenous bacteria proliferate deeply into mucous membrane. This proliferation is monitored by neighboring FAE of mucous lymphatic follicles.5. At bacterial attachment sites, indigenous bacteria are eliminated by both the physical defense of rearrangement of epithelial cytoskeletons and the chemical defense of secretion of antibactericidal substances.6. The detailed differentiation and re differentiation processes were clarified in FAE of Peyer's patches under transmission electron microscope.