Functional morphology of microfold cells (M cells) in Peyer's patches--phagocytosis and transport of BCG by M cells into rabbit Peyer's patches.
Suspensions of BCG (32-80 X 10(7) viable bacilli/ml) were injected into constricted loops of ileum containing a Peyer's patch from non-immunized young adult rabbits after laparotomy under anesthesia. Light microscopically (rhodamine B-auramine double staining, Ziehl-Neelsen staining), many mycobacteria were observed adhering to the surface of follicle-associated epithelium (FAE) and in phagocytes that had migrated within FAE and to deep lymphoid follicles. Electron microscopically in 1-hour post inoculated specimens, the bacteria were found adhering specifically to M cells, and the microfolds of the M cells were seen to stretch like tentacles toward the bacteria to catch them. The bacteria were recognized in the large vesicle of the cytoplasm of the M cells. The bacteria phagocytized by the M cells were found in the intercellular space between M cells and columnar cells. The bacteria were also seen in macrophages enfolded by the M cells as well as in macrophages below the FAE. In this experiment, BCG were found to have been phagocytized only by M cells, and none were found in absorptive cells. It was verified that M cells are the first entrance through which BCG invade the host and that they are transported from M cells to macrophages of the epithelium.
D000818:Animals; D001500:BCG Vaccine / Q000378:metabolism*; D001692:Biological Transport; D008264:Macrophages / Q000276:immunology; D008297:Male; D008854:Microscopy, Electron; D010581:Peyer's Patches / Q000378:metabolism / Q000648:ultrastructure*; D010587:Phagocytosis; D011817:Rabbits
D001500:BCG Vaccine