FINE STRUCTURE OF RICKETTSIA QUINTANA CULTIVATED IN VITRO AND IN THE LOUSE.

Ito, Susumu (Harvard Medical School, Boston, Mass.), and J. W. Vinson. Fine structure of Rickettsia quintana cultivated in vitro and in the louse. J. Bacteriol. 89:481-495. 1965.-Usually rod-shaped, Rickettsia quintana cells measure about 0.2 to 0.5 mu wide and up to 1.6 mu long. The rickettsiae have both an outer cell wall, about 80 A thick, and a plasma membrane, about 70 A thick, each of which is trilaminar. Occasional vesicular invaginations of the plasma membrane occur. The nuclear material, distributed in irregular zones throughout the cytoplasm, appears as a loose network of fine fibrils when postfixed with uranyl acetate and as thick strands or clumps after routine OsO(4) fixation. The cytoplasm is densely packed with numerous granules, presumably ribosomes, about 150 A in diameter. Histochemical studies revealed the presence of both ribonucleic and deoxyribonucleic acids. During binary fission, a constricting furrow is formed by the cell wall and plasmalemma. No difference in fine structure was observed between R. quintana propagated on cell-free media and in the louse.