title: Outer envelope of virulent Treponema pallidum.
abstract: Ultrathin sections of virulent Treponema pallidum (Nichols strain) were examined with the electron microscope, and the presence of an outer cell envelope was documented.
mesh_terms: D000818:Animals; D002473:Cell Wall; D007109:Immunity; D008297:Male; D008854:Microscopy, Electron; D011817:Rabbits; D013587:Syphilis / Q000276:immunology; D013737:Testis / Q000382:microbiology; D014210:Treponema pallidum / Q000166:cytology*; D014774:Virulence