Fine structure of Calymmatobacterium granulomatis with particular reference to the surface structure.

Ultrastructural study of C. granulomatis, the causative organism of donovanosis (granuloma inguinale), in human tissue revealed the presence of a complex cell envelope. The cytoplasm of these organisms showed presence of electron dense polar material, in addition to regular bacterial structures like mesosome, ribosomes, and nuclear material. Surface appendages i.e., fimbriae and blebs were studied in detail. Origin of these structures was clearly endogenous to the cell wall. Morphology of fimbrium at the site of its attachment to the cell membrane has been described. A distinct layer of homogenous material of varying density surrounding the organism indicated the possibility of it being a capsule.