[Electron microscopic study of the I, II phases and R-forms of Sh. sonnei].

Electron microscopic study of the microbial cells of the I, II phases and the R-form was carried out. Intact cells were examined by negative contrasting, and morphological differences of various bacterial phases were shown: cells of the I phase had a relatively smooth surface, bacteria of the II phase had a smooth surface, but many cell wall fragments were split from them; the surface of the R-form cells was coarse, folded, and cell wall fragments were split from the majority of bacteria. Antigenic determinants responsible for phasic specificity in bacteria of the I and II phases were located at some distance from the external membrane of the cell wall; as to the R-form cells--they were localized on the wall.