[Dissociation and ultrastructure of the cells of Shigella sonnei isolated from gnotobiotes and obtained in vitro].

The dissociation variants of S. sonnei in phase I, isolated from germ-free rats and obtained in vitro, have been studied. Such dissociation variants have been found to form colonies with classical and atypical morphology. The electronmicroscopic study has revealed that different dissociation variants include small dense cells with the markedly thickened cell wall and pronounced microcapsule and spheroplasts with the damaged cell wall and less pronounced microcapsule. The formation of these cells is supposed to be the way of the adaptation of S. sonnei in the course of the infectious process and linked with changes in their virulence in the population cycle.