Talk about the heterogeneity of cardiac muscle cells (Cardionector)

Cardionector cells: They are modified cardiac cells specialized in the initiation and conduction of contraction of the myocardium. They differ according to their anatomic localization: - Nodal cells (cells of the sino-atrial node and atrio-ventricular node): they are small, contain very few myofibrils, and are devoid of T tubules. - Cells of the bundle of His: they are larger than nodal cells. Their myofibrils are well organized and parallel. - Purkinje cells: they are huge and contain very few myofibrils.