Ultrastructural study of the myocardial wall of the atrio-ventricular canal during the development of the embryonic chick heart

Abnormal Conduction and Morphology in the Atrioventricular Node of Mice With Atrioventricular Canal–Targeted Deletion of Alk3/Bmpr1a Receptor

“…This coincides with the detection of slow AV conduction through the canal. [21][22][23] If tight cellular connections were maintained between even a portion of AV myocytes, it could lead to the accessory pathways observed in class II and III hearts in the present study. Formation of the AV node and the His bundle occurs as the endocardial cushions fuse, the central fibrous body forms, and ventricular septation is complete, with only 1 pathway left for impulse conduction.…”

Genetic Wiring Diagram of the Cardiac Conduction System

“…The annulus fibrosus simultaneously forms to insulate the atrial from the ventricular myocardium. 16,17 In addition, some myocytes at the inner curvature of the looping heart tube are specified to become the AV node. 18 One can reasonably hypothesize that BMP signaling regulates each of these processes in combination with other developmental inputs.…”

A Beat Is Born: Embryonic Development of Arrhythmogenesis

“…The provocation of arrhythmias in the embryonic heart is an emerging field, fostered in part by the clinical impetus for improved fetal diagnostics and interventions. In the developing heart tube, the atrium and ventricle are in electrical continuity around the circumference of the atrioventricular (AV) canal musculature 1 . Both fusion of the AV sulcus with endocardial cushions tissue and loss of cell‐to‐cell contact in the AV canal mature to eventually allow separation between atrial and ventricular myocardium 2,3 .…”

“…In the developing heart tube, the atrium and ventricle are in electrical continuity around the circumference of the atrioventricular (AV) canal musculature. 1 Both fusion of the AV sulcus with endocardial cushions tissue and loss of cell-to-cell contact in the AV canal mature to eventually allow separation between atrial and ventricular myocardium. 2,3 Development of an AV delay in the embryonic chick heart is coincident with the dissociation of intercalated disks and desmosomes between myocytes in the AV canal and an increase in the extracellular matrix between the cells, not seen in atrial or ventricular muscle.…”