Abnormal cardiomyocyte mitochondrial morphology Intranuclear cardiomyocyte mitochondria 2017-08-27T13:30:13Z Abnormal localization of mitochondria within the nuclei of cardiomyocytes. Electron microscopy of mammalian cardiac and skeletal muscle tissues reveal mitochondria as individual organelles situated either in clusters beneath the sarcolemma (subsarcolemmal mitochondria) or in longitudinal rows within the contractile apparatus (interfibrillar mitochondria).