Electron Microscopy of T‐strains

Abstract

T-Strains have several characteristics in common with the genus Mycoplasma. Whether or not they are, in fact, mycoplasma has, on occasion, been questioned. One of the main criticisms has been the lack of electron-micrographs showing the morphology of these organisms.Two T-strains from the human genital tract, one from the bovine genital tract and one from the human oropharynx were examined by electron-microscopy. For this purpose, the strains were grown in medium without serum. It was not possible, however, to subculture these organisms in serum-free medium.Cultures of the organisms were incubated for 36 hours at 37°C. Cells were deposited by centrifuging 80 mls of each culture at 60,000 g and then resuspended in 2.0 mls of the supernatent. Fixing the cells with 4.0% glutaraldehyde while still in suspension was found to produce clumps which could not be easily dispersed. Furthermore, addition of 2% phosphotungstic acid to a cell suspension so fixed produced a precipitate which obscured the cells. Uninoculated medium treated in exactly the same way did not exhibit this phenomenon.Specimens were therefore prepared by placing one drop of the cell suspension on carbon-coated grids and fixing in formalin vapour for 30 seconds before staining with phosphotungstic acid. Prepared in this way, cultures were found to contain cells ranging from 800 rnp down to 150 to 160 m p ( FIGURES 1 a and 2). These cells appear to have an asymetric membrane with the outer component being more electron dense than the inner one. Lying outside the limiting membrane is frequently found an envelope of material which is thought to be lipid in nature. Within this envelope there can be seen, on occasion, structures resembling spikes (FIGURE 1 b). Spherical cytoplasmic condensations about 40 to 50 my. in diameter can be seen in most of these cells (FIGURE 2). A further feature is shown in FIGURE 3a, where the cytoplasmic condensations have been liberated from a ruptured cell. It is possible that these represent minimal reproductive units and are shown at a higher magnification in the following FIGURE 3b, where their size is about 65-70 mp.Further studies of behavior in density gradients, examination of ultra-thin sections and an investigation of the relationship of cell size to viability are in progress. The aim of this brief communication has been to suggest that T-strain organisms do not differ fundamentally from other mycopalsma. 391

In Vitro Exposure of Bovine Morulae to Ureaplasma Diversum

“…This study illustrates that U. diversum strain 2312 attaches to the outer surface of the bovine zona pellucida, that ureaplasmas do not penetrate the zona pellucida and that the organism does not cause morphological changes in bovine morulae following 16 hours incubation in vitro. The cellular morphology of U. diversum strain 2312 is identical to that described previously for U. urealyticum and U. diversum (24,25,26,27,28).…”

Morphology and Ultrastructure of Human T-Mycoplasmas

“…After solidification, small agar blocks (about 1 mm') with cells embedded were cut and fixed for 1 hr at room temperature (20-22 C) in 3% GA in VA buffer to which was added one part of YAP medium (yeast extract-sodium acetate-peptone medium [0.3%, 0.05%, and 0.3%, respectively; Difco products]) to ten parts of fixative (v/v). After this fixation, the agar blocks were rinsed twice with 0.2 M sucrose in VA buffer, pH 6.1, and stored overnight at 4 C. The blocks were then rinsed twice in pure VA buffer and then fixed ovemight (17) at room temperature (20)(21)(22) C) in 1% VA-buffered Os04 to which was added one part of YAP medium to ten parts of fixative. After a brief wash in VA buffer and a 1-hr treatment at 20 to 22 C with 2% uranylacetate in the same buffer, the agar blocks were dehydrated in 70%, 96%, and 100% alcohol, briefly treated with propylene oxide, and fialy embedded in Vestopal-W (18).…”

T-Mycoplasmas: A Study of the Morphology, Ultrastructure and Mode of Division of Some Human Strains

“…Electron microscopy (EM) confirmed these observations and also showed that the cells divide primarily by budding in different directions, producing poly-directional growth ramifications (Shepard, 1969). The outer membrane is trilaminar with a surface layer of hair-like structures (Williams, 1967), and each coccus contains vacuoles and ribosomes, some of which may be arranged in geometrical patterns (Black, Birch-Andersen and Freundt, 1972).However, some more recent EM studies of thin sections and negatively stained preparations (Black et al, 1972) have described the organisms as short rods and filamentous forms with branches and terminal club-shaped swellings, rather than as spherical bodies embedded in a gelatinous matrix. In an attempt to resolve these differences we have examined the gross morphology and ultrastructure of five laboratory strains isolated from patients with nonspecific urethritis (NSU) (Furness, 1973), by several light-and electron-microscope techniques.…”