Origin of Conducting System of the Heart

In the attached video you can find the relevant information regarding the development of conducting system of the heart and the origin of structures from different primitive parts along with the development timeline. Timeline: 0:00 - Development of cardiac muscle fibers 1:49 - Development of AV node and AV bundle 4:29 - Development of SA node 6:43 - Myocardial contractions 10:22 - Summary