THE STRUCTURE OF MYCOPLASMA-PNEUMONIAE AS DETERMINED BY THE FREEZE-SUBSTITUTION TECHNIQUE

The ultrastructure of Mycoplasma pneumoniae FH was examined by a mild fixation method, the freeze-substitution technique, for thin-section t ransmission electron microscopy and the following new findings were ob tained. In the cytoplasm, no nuclear region could be clearly identifie d. The cytoplasm was filled with many ribosome-like particles, fine fi bers and electron-dense particles. The electron-dense particles appear ed to be similar to the particles found in the nucleoid region of Pseu domonas aeruginosa and might therefore possibly be a kind of DNA bindi ng protein. The cell surface was completely enveloped with a thin opaq ue layer. The presence of this surface layer prevented any direct cont act of the cell surface with that of the two M. pneumoniae cells.