In the crista terminalis region, the atrial cells are the predominant cell type (63±18%) and are accompanied by a subset of elongated spindle nodal cells. On the contrary, in the septal area is largely consistent of atrial cells (88±19%) while maintains a uniform presence of all four types of sinoatrial node cells: Elongated spindle-shaped cells, Spindle cells, Spider cells and Atrial cells.

Action potentials pass from one cardiac cell