Editing Mycobacterium tuberculosis (section)

=== Microscopy ===
[[File:M.tuberculosis.jpg|thumb|Growth of ''Mycobacterium tuberculosis'' on Löwenstein-Jensen (A) and Ogawa medium (B), after six weeks at 37°C.]]
Other bacteria are commonly identified with a microscope by staining them with [[Gram staining|Gram stain]]. However, the mycolic acid in the cell wall of ''M. tuberculosis'' does not absorb the stain. Instead, acid-fast stains such as [[Ziehl–Neelsen stain]], or fluorescent stains such as [[Auramine O|auramine]] are used.<ref name=":0" /> Cells are curved rod-shaped and are often seen wrapped together, due to the presence of fatty acids in the cell wall that stick together.<ref>{{Cite web |url= http://textbookofbacteriology.net/tuberculosis.html |title= Mycobacterium tuberculosis and Tuberculosis |vauthors= Todar K |website= textbookofbacteriology.net |access-date= 2016-12-24 |archive-date= 24 December 2016 |archive-url= https://web.archive.org/web/20161224162909/http://textbookofbacteriology.net/tuberculosis.html |url-status= live}}</ref> This appearance is referred to as cording, like strands of cord that make up a rope.<ref name=":1" /> ''M. tuberculosis'' is characterized in tissue by caseating [[granulomas]] containing [[Langhans giant cell]]s, which have a "horseshoe" pattern of nuclei.{{citation needed|date=May 2024}}