title: Ultrastructure of Bacteroides species: Bacteroides asaccharolyticus, Bacteroides fragilis, Bacteroides melaninogenicus subspecies melaninogenicus, and B. melaninogenicus subspecies intermedius.
abstract: Representative strains of two subspecies of Bacteroides melaninogenicus (subspecies melaninogenicus and subspecies intermedius) and Bacteroides asaccharolyticus as well as B. asaccharolyticus strain 536B isolated from a human perirectal abscess and Bacteroides fragilis ATCC 25285 were examined by glutaraldehyde-osmium fixation, ruthenium red fixation and staining, and thorium hydroxyde staining as well as by the physical preparative techniques of critical point drying--transmission electron microscopy (CPD--TEM) and scanning electron microscopy (SEM). All strains, with the exception of B. fragilis 25285, possessed an electron-dense material external to their outer membranes. Ruthenium red staining further revealed a layer, external to the surface of the outer membrane, that was distinct for each species examined. Thorium hydroxide, as well as CPD--TEM and SEM, showed the cells to be interconnected by thin fibers that not only connected adjacent cells but also traversed several microns to connect cell aggregates.
mesh_terms: D001439:Bacteroides / Q000648:ultrastructure*; D001441:Bacteroides fragilis / Q000648:ultrastructure; D005404:Fixatives; D005976:Glutaral / Q000494:pharmacology; D009992:Osmium / Q000494:pharmacology; D001443:Prevotella melaninogenica / Q000648:ultrastructure; D012430:Ruthenium Red / Q000494:pharmacology; D013194:Staining and Labeling; D013910:Thorium / Q000494:pharmacology
chemical_list: D005404:Fixatives; D012430:Ruthenium Red; D009992:Osmium; D013910:Thorium; D005976:Glutaral