Cox negative fibers are typically identified using histochemical staining techniques. The most common method involves a dual staining process combining COX and succinate dehydrogenase (SDH) staining. In this process, muscle tissue sections are first stained for COX activity; fibers that do not stain (appear negative) are then subjected to SDH staining, which marks mitochondrial activity. Cox negative fibers will show a lack of COX staining but will still exhibit SDH activity, appearing blue.
