STRUCTURAL STUDIES OF THE SURFACE PROJECTIONS OF CHLAMYDIA-TRACHOMATIS BY ELECTRON-MICROSCOPY

Rod-like projections on the surface of Chlamydia trachomatis have been studied by a combination of computer image analysis and electron micr oscopy. The rods, c. 60-80 Angstrom in diameter and c. 500 Angstrom in length, were found on the surface of prokaryocells of C. trachomatis inserted in the cytoplasmic membrane through a ring-like structure in the outer membrane. The rod-like structures were found at all stages o f the life cycle, even in very small elementary bodies (EBs) of C. tra chomatis and in vesicles, 0.2 mu m. Computer image analysis of isolate d rods indicated that they comprise helically arranged subunits with a periodicity of c. 50 Angstrom. From their localisation and distributi on, these structures may be related to the proliferation, or to the in fectivity, of chlamydiae.