histological sample heart muscle tissue under the microscope.

anatomy animal atrium background biology blood cardiac cell cells central disease education fiber fibres health heart hematoxylin histological histology human infarction intercalated isolated joined laboratory medical medicine micrograph microscope microscopic microscopy muscle muscles muscular myocardial myocardiocyte myocardium myocytes myofibril myofibrils nucleus peripheral physical research sample science scientific section skeletal smooth striated structure study system tissue white