Electrophysiological properties of ESCM isolated at D7+2–4 and D7+5–11.

Specialization of the cells was based on the action potential parameters: resting membrane potential (Vm), AP duration at 50% of repolarisation (APD50%) and amplitude of the AP. Shown are data of primary myocardial-like, atrial-, ventricle- and sinus node-like cells. At D7+2–4, 7 of 8 cells displayed features typical of immature primary myocardium and one cell was AV-like; whereas, between D7+5–11, all but three cells displayed a more mature phenotype typical of atrium, ventricle and nodal regions (sinus and atrio-ventricular).