High magnification electron micrograph of an ultra-thin section of a group A streptococcus sibling pair. At this magnification, especially in the cell on the left, the cell wall and cell surface fibrils, consisting primarily of M protein, are well defined. Interdigitaion of these fibrils between neighboring cells of different chains is also in plain view. Strain: C126/21/1; M-type 43.

(70,000X)