Ultrastructural Studies of Treponemes: Location of Axial Filaments and Some Dimensions of Treponema pallidum (Nichols strain), Treponema denticola , and Treponema reiteri

Abstract

Ultrathin sections of Treponema pallidum (Nichols strain), T. denticola (microdentium), and T. reiteri have been studied in the electron microscope to determine the location of the axial filaments and some of the dimensions of these organisms. The axial filaments of T. pallidum (Nichols strain) have been seen to be tubular in cross section with an overall diameter of 21.0 + 0.73 nm, and an electron-lucent core of 8.0 nm. The filaments were found to lie on the outside of the organism which had only one membranous structure surrounding the protoplasmic core. These findings were in contrast to those obtained for T. denticola and T. reiteri where the axial filaments did not exhibit a hollow core and were located between an outer membrane and an inner membrane surrounding the protoplasmic core. The outside diameter of T. denticola was determined to be 224.9 + 2.83 nm, and that of T. reiteri as 331.0 + 4.15 nm, contrasting with T. pallidum (Nichols strain) which had a diameter of 163.0 4 1.9 nm. Swain (11), in a comparative electron micro-

Avoidance of Host Defences by Treponema pallidum in Situ and on Extraction from Infected Rabbit Testes

“…The existence of an outer envelope external to the cell wall and periplasmic fibrils of T. pallidum has long been postulated (Christiansen, 1963), and more recent observations on treponemes in infected testes indicated an outer membrane covering the periplasmic fibrils (Johnson et al, 1973). The apparent absence of such an outer membrane in the preparation described here raises doubts about its existence which have been expressed previously (Sykes & Miller, 1973) following examination of organisms extracted from tissue. Holt (1978) suggested that differences may have been due to differences in procedure, but the fixation of tissue described here was essentially similar to that used by Johnson et al (1 973), and the possibility of differences between strains used in different laboratories cannot be excluded.…”

Antigenic interrelationship between endoflagella of Treponema phagedenis biotype Reiter and Treponema pallidum (Nichols): molecular characterization of endoflagellar proteins

“…In view of the known molecular (31), antigenic (15), and ultrastructural (35) differences between the endoflagella of T. pallidum and T. phagedenis, it appears likely that the endoflagella of T. pallidum possess unique epitopes which may play a role in the immunopathogenesis of syphilis. The study of their contribution to syphilis pathogenesis will, therefore, necessitate the isolation and characterization of these structures from T. pallidum.…”

Anatomy and chemistry of spirochetes.

“…Although an outer sheath was said to be absent in thin sections of T. pallidum Nichols (205), Johnson and co-workers (109) have shown quite clearly the presence of a triple-layered outer sheath in their strain of T. pallidum Nichols. It seems likely that these conflicting reports stem from examination of freshly isolated cells fixed with a minimum of preparatory steps (109), as opposed to the examination of cells fixed after extensive manipulative steps (205).…”