title: Ultrastructural study on the epithelial responses against attachment of indigenous bacteria to epithelial membranes in peyer's patches of rat small intestine.
abstract: The ultrastructure of epithelial responses against the membrane adhesion of indigenous bacteria was investigated in the follicle-associated epithelium (FAE) of rat small intestine. The most frequent adherence of the various morphological types of bacteria to the epithelial membranes was found at the apex of the FAE. The attachment sites were deeply invaginated, and their bottoms were deformed into a sharp cone shape. Four layers with different electron densities were formed just beneath the apical membranes by microfilaments which surrounded the invaginations. The electron density of each layer was gradually decreased as being apart from the invaginations. The extremities of some bacteria in the invaginations were deformed into sharpened shapes. The cell walls of the extremities of the bacteria were occasionally dissolved in the invaginations, and their cytoplasms were slightly swollen with low electron densities. In some invaginations, the attached bacteria were eliminated to leave their fragments such as filamentous debris and a part of cell walls. Finally these remnants disappeared completely. When the bacterial colonies existed in the middle region of the FAE, the attachment of bacteria resulted in the engulfment of bacteria by M cells. The degenerated bacteria whose cytoplasmic matrices were separated into high electron dense materials and cleared materials were occasionally engulfed by ordinary microvillous columnar epithelial cells or goblet cells throughout the FAE. These findings suggest that the epithelial cells reject the attachment of live indigenous bacteria and that the M cells absorb indigenous bacteria in rat Peyer's patches.
authors.affiliation: Department of Bioresource and Agrobiosciences, Graduate School of Science and Technology, Kobe University, Kobe, Japan.
authors.forename: Tetsurou
authors.initials: T
authors.lastname: Inamoto
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawata
authors.forename: Wang-Mei
authors.initials: WM
authors.lastname: Qi
authors.forename: Kenkichi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Warita
authors.forename: Junichi
authors.initials: J
authors.lastname: Kawano
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hoshi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D001419:Bacteria / Q000648:ultrastructure*; D001422:Bacterial Adhesion / Q000502:physiology*; D007413:Intestinal Mucosa / Q000502:physiology*; D008297:Male; D046529:Microscopy, Electron, Transmission; D010581:Peyer's Patches / Q000382:microbiology* / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar