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

Abstract

PLATES XVIII AND XIX RELATIVELY little is known about the gross morphology, mode of division and ultrastructure of the T-mycoplasmas. In stained preparations viewed by light microscopy they appear as uniform, minute coccoid particles, about 0.3 pm in diameter, embedded in a gelatinous matrix (Ford and MacDonald, 1963 ;Shepard, 1967). Fluorescence microscopy after acridine-orange staining indicates that they are rich in RNA and DNA (Shepard, 1967). 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. MATERIALS AND METHODSThe formulae of the T-mycoplasma broth and agar media, T-broth and T-agar (Furness, 1973), and the techniques for preparing stock cultures (Furness, 1969), titrating viable T-mycoplasmas by colony counts (Furness, Pipes and McMurtrey, 1968), and obtaining single-cell suspensions by sonication and filtration through Millipore or Nalgene membranes (Furness, 1969) have all been described before. Deposition of organisms from suspension was always carried out at 14,508 g for 30 min.

In Vitro Exposure of Bovine Morulae to Ureaplasma Diversum

“…The structures observed on the outer surface of the zonae pellucidae of nine of the nine embryos experimentally exposed to U. diversum were morphologically identical to the small, granular forms observed in the U. diversum preparation, and those described previously in the early logarithmic phase of ureaplasma growth (27). On the basis of the presence of structures morphologically identical to U. diversum on the zonae pellucidae of all nine embryos exposed to U. diversum strain 2312 and the absence of similar structures on embryos not exposed to the organism, it was concluded that U. diversum strain 2312 attached to the outer surface of the bovine zona pellucida.…”

“…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).…”

A requirement for flow to enable the development of Ureaplasma parvum biofilms in vitro

“…A further observation from the SEM images was the presence of budding and potentially the formation of membrane vesicles. Budding has previously been observed among ureaplasmas, but little is known with regards to the formation of membrane vesicles (Whitescarver and Furness 1975). Finally, from the SEM images, structures which resembled suspected conjugation pili were apparent.…”

Ultrastructural Changes during the Life Cycle of Mycoplasma salivarium in Oral Biopsies from Patients with Oral Leukoplakia

“…The replication mode of M. salivarium in the epithelial cells was confirmed to be by equal or unequal binary fission by images showing invagination of membranes and formation of a cross-septum, when using the ultracryotomy immunolabeling method. A previous study that investigated the cell division of T-Mycoplasma by EM reported that invagination of bound membrane was seen, but no cross-septum was seen (Whitescarver and Furness, 1975 ). In this study, both invagination and cross-septum formation were observed.…”