Phase-Contrast and Electron Microscopy of Murine Strains of Mycoplasma

Abstract

Two strains of Mycoplasma pulmonis (associated with infectious catarrh) on examination in fluid culture (20% horse serum-bouillon) by phase microscopy were highly pleomorphic, with many bacilliform elements and fewer coccoid ones. Motility, characterized by gliding of rods and spinning of spherical forms, was observed through the 9th subculture of one strain and the 15th of the second. Motile elements were not seen in later transfers and pleomorphism was reduced. One strain of M. neurolyticum (associated with conjunctivitis and encephalitis) was much less pleomorphic and showed neither bacilliform elements nor motility at any time. When examined by negative-contrast electron microscopy, organisms of this strain were found to have an average diameter of 0.7 ,u and to possess a concentrated peripheral layer of cytoplasm and a central mass which may represent the cells' nuclear equivalent. The latter feature was not prominent in spherical forms of M. pulmonis. These cells, when observed after 48 hr of culture, showed evidence of the generation of new progeny cells in their central area. The filamentous or bacilliform cells of M. pulmonis were frequently serpentine in appearance, 2.0 to 3.0 it in length and 80 to 250 m,u in width. They appeared to generate new cells from terminal buds from which outpouchings initially developed. Older cells, in the stationary phase, showed evidence of undergoing multipolar germination. Microtubules, about 60 m,u wide, were found in association with most filamentous cells from 48-hr cultures; fragments of membrane, studded with closely packed ribosomelike particles, were also found. There was no evidence of flagella or any specialized structure that could account for the observed motility of the organisms.

Fine Structure and Location of the Mycoplasma-like Gray Lung and Rat Pneumonia Agents In Infected Mouse Lung

“…On the first account, M. hominis processed as a control by the same methods did not differ from previous descriptions of its fine structure (1). On the second account, M. pulmonis in diseased mouse lung has been found to be identical in fine structure with forms described in vitro (15,16). Perhaps the unique morphology of the gray lung and rat pneumonia agents may .T u The unit serve to define a new species within the genus Mycoplasma.…”

Ultrastructural Features of Mycoplasma pneumoniae

“…Alternatively, the peripheral localization of this structure may suggest that it is concerned with the locomotion of the organisms. However, motility has also been observed in some strains of M. pulmonis, but these organisms had no similar specialized structure that could account for the motility (12).…”

Changes in epithelial secretory cells and potentiation of neurogenic inflammation in the trachea of rats with respiratory tract infections

“…For example, an active infection by M. pulmonis was present. This was evidenced by high serological titers to the organism, electron microscopic visualization on the airway epithelium of organisms with the typical morphology of M. pulmonis (Nelson and Lyons 1965), and characteristic pathological changes in the airway mucosa (Lindsey et al 1971). Furthermore, the abnormally large amount of plasma extravasation associated with neurogenic inflammation in the infected rats appeared to be due in part to the proliferation of blood vessels, which is one of the manifestations of chronic infections such as those caused by M. pulmonis.…”