“…Examination of thin sections of filamentous M. pneumoniae by transmission electron microscopy likewise reveals an electron-dense core extending the length of the attachment organelle (8,13,33,34). The core structure has a striated appearance or periodicity, suggesting that it contains repeating subunits (22,33). Furthermore, the core structure terminates in a knob formation at one end and has fibers extending from the opposing base into the matrix of the cell body (3,33,34), which is similar in appearance and organization to the triton shell (22).…”