Electron Microscopic Studies of the Morphology and the Stages of Development of Mycoplasma gallisepticum

Abstract

The morphology and the stages of development of M. galli-septicum (S3 strain) in broth culture were studied with the electron microscope using a negative staining technique. Large cells predominate in young cultures. These are usually spherical, from 500- 600 mu in diameter. A nucleus-like structure subsequently becomes visible in these large cells and undergoes various stages of development and division. The large cells multiply by a process resembling budding in 18-21-hr, cultures, resulting in the production of small and large daughter cells. The daughter cells are the predominant cell types, the large daughter cells being the more predominant in 24-30-hr. cultures. The large daughter cells are irregularly spherical, with 1 end slightly tapered for attachment to the mother cells. Most of them remain attached to the mother cells, but a few are detached and remain free. The small daughter cells are single cells which are spherical-, dumbbell-, and club-shaped and 150-300 mu in size. Large spherical cells of 450-500 m[mu] in diameter predominate in 30-36-hr. cultures. These cells do not show a distinct nucleus-like structure. On further incubation of the cultures no significant changes of the cells are observed. A developmental cycle of M. gallisepticum is suggested.