Heart rate date normally used to date pregnancy in the medical community. The electrical depolarizations that trigger cardiac myocytes to contract arise spontaneously within the myocyte itself. The heartbeat is initiated in the pacemaker regions and spreads to the rest of the heart through a conduction pathway. Pacemaker cells develop in the primitive atrium and the sinus venosus to form the sinoatrial node and the atrioventricular node respectively. Conductive cells develop the bundle of His and carry the depolarization into the lower heart. The human heart begins beating at a rate near the mother’s, about 75–80 beats per minute (bpm). The embryonic
Cardiac neural crest cells of heart attacks include cardiac arrhythmias and heart failure. Although CNCCs are important in embryos, some CNCCs are retained in a dormant state to adulthood where they are called "neural crest stem cells". In 2005, Tomita transplanted neural crest stem cells from mammal hearts to the neural crest of chick embryos. These CNCCs were shown to migrate into the developing heart of the chick using the same dorsolateral pathway as the CNCCs, and differentiate into neural and glial cells. Tamura's study of 2011 examined the fate of CNCCs after a heart attack (myocardial infarction) in young mice. The CNCCs in