Morphologic Characteristics of Certain Cultured Strains of Oral Spirochetes and Treponema pallidum as Revealed by the Electron Microscope

Publisher Website
Google Scholar
Abstract
In this investigation 8 pure cultures of spirochetes were employed. Two of these were strains of the small oral treponemes, 4 were strains of Borrelia vincentii, and 2 were cultured strains of Teponema pallidum. Approx. 300 metal-shadowed specimens were made for electron microscopic study from more than 30 cultures. The morphologic and finer structural features were studied in detail. The external appearance of all types of spirochetes studied were strikingly similar. Definite cell membranes were not observed. Most surfaces were irregular and may be an expression of uneven distribution of cytoplasm. Terminal filaments were present on all spp. of spirochetes and were not single fibers, but consisted of intertweined fine strands. No evidence was found to indicate that these structures were derived from the cell walls. Flagella were found attached along the side of all the strains of spirochetes; they occurred singly or in tufts and occasionally intertwined to form cords. The internal, end and external granules were found in all the spp. of spirochetes. The external granules arise in intimate association with the spirochetal cell; the contents are seemingly like the cytoplasm of the organism and blend with it. None of the granules were attached by stalks. Typical free granules, the end product of granule " shedding," were roughly circular in outline and sharply bounded. They consisted for the most part of what appeared to be short sections of spirochetes closely packed together.