Microscopically, intramuscular blood and gas bubbles separate swollen eosinophilic myofibers, many of which are hyalinized but retain their cross striations. Other myofibers are fragmented, with shredded or granular sarcoplasm and pyknotic nuclei. Necrotic myofibers are often accompanied by lysed erythrocytes and small collections of neutrophils in the endomysium and perimysium (see arrows below). Individual fibers and whole fascicles may be disrupted by variably-sized cavities (gas bubbles) in the endomysium and perimysium. Distributed within the affected areas are few to many gram-positive bacilli.