FINE STRUCTURE OF CELL WALL AND CYTOPLASMIC MEMBRANE OF CLOSTRIDIUM NIGRIFICANS DEMONSTRATED BY MEANS OF FREEZE-ETCHING AND CHEMICAL FIXATION TECHNIQUES

A comparison was made between the results obtained using the freeze-etching technique in demonstrating the fine structure of the cell wall and the cytoplasmic membrane of Clostridium nigrificans with those using the chemical fixation technique. In chemically fixed cells, the cell wall appears to consist of three dense layers separated by two layers of low electron scattering power, whereby it is not always possible to observe that layer immediately bordering on the cytoplasmic membrane. The cytoplasmic membrane has an asymmetrical unit membrane structure. It was possible, to separate the cell wall in three distinct layers using the freeze-etching technique. The outermost is composed of globular, rectangularly arranged particles, approximataly 9 nm in size, the two inner layers are 15 and 5 nm wide respectively. The cytoplasmic membrane is covered with particles 5 to 15 nm in size, in younger cultures completely, in older cultures partially. On those places where the particles have been split off or where they are loosly arranged, it was possible to observe the surface of the cytoplasmic membrane. It appears to be covered with unsystematically scattered particles imbedded at different depths, not only on that side turned to the cell wall but also on that facing the cytoplasm. © 1969 Springer-Verlag.