Open AccessJournal Article
The early development of the atrioventricular node and bundle of His in the embryonic chick heart. An electrophysiological and morphological study.
TLDR
It is concluded that the AV node and upper bundle of His cells derive from the low interatrial septum, which has similar characteristics to those of the adult heart.Abstract:
The development of the atrioventricular node and bundle of His of embryonic chick hearts was studied by electrophysiological and morphological techniques. The dorsal wall of the AV canal and the interatrial septum were explored to determine if they contribute to the formation of the AV node and bundle of His. The resting membrane and action potentials of the interatrial septum cells were systematically analyzed and found to undergo progressive differentiation with development. The earliest identification of the AV node and upper bundle of His group of cells was achieved at 5 1/2-6 days of development by the electrical recording of their corresponding characteristic action potentials, from a circumscribed area located in the lowest and dorsal segment of the interatrial septum. The morphological and anatomical characterization of the cells was made following electrical recording and labelling with charcoal particles. The earlier AV node and bundle of His responses had similar characteristics to those of the adult heart. It is concluded that the AV node and upper bundle of His cells derive from the low interatrial septum. The possibility that AV canal cells contribute to this event was discarded. The functional relationship of the Av node and bundle of His with other cardiac tissues during the early development of the heart is discussed.read more
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Persisting zones of slow impulse conduction in developing chicken hearts.
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TL;DR: The slowly conducting myocardial zones appear to be essential for the function of the embryonic heart because they provide the septating heart with alternating segments of slow and relatively fast conduction necessary for consecutive contraction of the atrial and ventricular segments and their sphincterlike prolonged peristaltic contraction pattern can substitute for the adult type of one-way valves that start to develop at the end of septation.
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The Tbx2+ Primary Myocardium of the Atrioventricular Canal Forms the Atrioventricular Node and the Base of the Left Ventricle
Wim T.J. Aanhaanen,Janynke F. Brons,Jorge N. Domínguez,M. Sameer Rana,Julia Norden,Rannar Airik,Vincent Wakker,Corrie de Gier-de Vries,Nigel A. Brown,Andreas Kispert,Antoon F.M. Moorman,Vincent M. Christoffels +11 more
TL;DR: It is found that the embryonic left ventricle only forms the left part of the definitive ventricular septum and the apex, and observations indicate that Tbx2 temporally suppresses differentiation and proliferation of primary myocardial cells.