The Development of the Cardiac Specialized Tissue

Anderson, Robert; Becker, Anton E.; Wenink, Arnold C. G.; Janse, Michiel J.

doi:10.1007/978-94-009-9726-4_1

Cited by 42 publications

(28 citation statements)

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“…Furthermore, AchE staining of conduction fibers in the midnodal zone of the AV node could be species as well as age dependent. 22 The compact node of the midterm human fetus is AchE-positive but not innervated, in contrast to the surrounding transitional zone. In the adult dog, the compact node appears both AchE-positive and richly innervated.…”

Section: Histochemical Findingsmentioning

confidence: 98%

Morphological and electrophysiological correlates of atrioventricular nodal response to increased vagal activity.

et al. 1990

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The mechanisms responsible for slowing cardiac impulse conduction through the atrioventricular (AV) node are not well understood but include anatomical architecture, presence of cells with diverse electrophysiological characteristics, and modulation by autonomic nervous system. The present study was designed to determine the site of vagally induced slowing of conduction through the AV node. We attempted to correlate the electrophysiological response of AV nodal cells to postganglionic vagal stimulation applied in different regions of the node with the morphological findings and patterns of acetylcholinesterase-positive staining of nodal tissue.This multifaceted approach revealed that vagal stimulation produced localized hyperpolarization of the cells from the N region of the AV node, which correlated with the strong acetylcholinesterase positive staining of the central nodal area. In contrast, the density of the acetylcholinesterase staining decreased toward both the AN and His bundle regions, whereas vagal stimulation had a negligible effect on the cells from these regions. These results suggest that vagal-induced depression of AV nodal conduction is produced by release of acetylcholine predominantly around the midnodal region and the depressive action of acetylcholine is concentrated on the cells occupying the same region (i.e., the N cells). Thus, there appears to be a close juxtaposition of nerve elements and effector cells in the midnodal region of the AV node. This unique combination of available neuromediator and responding cells with hyperpolarization and depressed action potential determines the midnodal region as the focus of vagal effect on AV nodal conduction. (Circulation 1990;82:951-964) Since the pioneering work of Tawara,' the atrioventricular (AV) nodal region has been the focus of intensive morphological and electrophysiological studies designed to identify the mechanisms of AV conduction. Yet there is still no unequivocal morphological classification of AV nodal zones in relation to the electrophysiological characteristics of the corresponding cells.

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Section: Histochemical Findingsmentioning

confidence: 98%

Morphological and electrophysiological correlates of atrioventricular nodal response to increased vagal activity.

et al. 1990

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“…As we discussed in the previous section, these areas indeed have a sphincter function and contribute to the slow components of the cardiac conduction system (the nodes, or pacemaking tissues). Later, the rings were retrieved from oblivion in studies on the development of the conduction system in human embryos, but their sphincter function was denied (330) and the rings were not explicitly restricted to the slowly conducting components of the conduction system, but to so-called "cardiac specialized tissue" (7,330). The latter term does not distinguish unambiguously between the slow and the fast components of the cardiac conduction system.…”

Section: F Tales Of the Rings: The Emerging Concept Of Ballooning Chmentioning

confidence: 99%

“…In our opinion, the question can justifiably be asked, whether these authors thought that the entire proximal bulbus would become the primitive right ventricle or merely the trabeculated part at the outer curvature? Others dispute the origin of the right ventricle in the bulbus cordis and argue that it is not a bulbar structure in its entirety (7). In fact, the latter authors may have called the proximal part of the bulbus mentioned by the authors of references (73,314), right ventricle.…”

Section: A Evolutionary Aspects and Terminological Problemsmentioning

confidence: 99%

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Cardiac Chamber Formation: Development, Genes, and Evolution

Moorman

Christoffels

2003

Physiological Reviews

648

526

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Moorman, Antoon F. M., and Vincent M. Christoffels. Cardiac Chamber Formation: Development, Genes, and Evolution. Physiol Rev 83: 1223-1267, 2003; 10.1152/physrev.00006.2003.—Concepts of cardiac development have greatly influenced the description of the formation of the four-chambered vertebrate heart. Traditionally, the embryonic tubular heart is considered to be a composite of serially arranged segments representing adult cardiac compartments. Conversion of such a serial arrangement into the parallel arrangement of the mammalian heart is difficult to understand. Logical integration of the development of the cardiac conduction system into the serial concept has remained puzzling as well. Therefore, the current description needed reconsideration, and we decided to evaluate the essentialities of cardiac design, its evolutionary and embryonic development, and the molecular pathways recruited to make the four-chambered mammalian heart. The three principal notions taken into consideration are as follows. 1) Both the ancestor chordate heart and the embryonic tubular heart of higher vertebrates consist of poorly developed and poorly coupled “pacemaker-like” cardiac muscle cells with the highest pacemaker activity at the venous pole, causing unidirectional peristaltic contraction waves. 2) From this heart tube, ventricular chambers differentiate ventrally and atrial chambers dorsally. The developing chambers display high proliferative activity and consist of structurally well-developed and well-coupled muscle cells with low pacemaker activity, which permits fast conduction of the impulse and efficacious contraction. The forming chambers remain flanked by slowly proliferating pacemaker-like myocardium that is temporally prevented from differentiating into chamber myocardium. 3) The trabecular myocardium proliferates slowly, consists of structurally poorly developed, but well-coupled, cells and contributes to the ventricular conduction system. The atrial and ventricular chambers of the formed heart are activated and interconnected by derivatives of embryonic myocardium. The topographical arrangement of the distinct cardiac muscle cells in the forming heart explains the embryonic electrocardiogram (ECG), does not require the invention of nodes, and allows a logical transition from a peristaltic tubular heart to a synchronously contracting four-chambered heart. This view on the development of cardiac design unfolds fascinating possibilities for future research.

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“…These observations regarding interatrial connections traversing the septum and connecting the coronary sinus with the left atrial musculature probably reflect the embryological development of this part of the heart. 25,26 From the third week after the development of the primitive heart tube, the primitive atria are separated from the sinus venosus (which forms the caudal extremity of the heart tube) by a segmentation termed the sinoatrial ring. The sinus venosus has 2 horns: the right horn gives rise to all the intercaval regions of the right atrium extending until the ostium of the coronary sinus and the precaval bundle and includes the crista terminalis, the eustachian ridge, and the valve of Thebesius; the left gives rise to the coronary sinus.…”

Section: Chauvin Connections Between Coronary Sinus and Left Atriummentioning

confidence: 99%

The Anatomic Basis of Connections Between the Coronary Sinus Musculature and the Left Atrium in Humans

et al. 2000

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Background-This study determined the histological features of the atrial myocardium connecting the coronary sinus and the left atrium in humans. Methods and Results-Ten necropsied hearts were studied by performing serial longitudinal sections parallel to the long axis of the coronary sinus that extended its full length using a large microtome. In all specimens, the venous wall of the coronary sinus was surrounded by a cuff of striated muscle extending 40Ϯ8 mm from the ostium. Striated myocardial connections of varying number and morphology left this coronary muscle cuff and connected to the left atrium; they ranged from 1 to 2 fascicles to a widely intermingled continuum (thickness, 2.79Ϯ2 mm; width, 2.91Ϯ3.5 mm). These connections originated 8.8Ϯ5.7 mm from the coronary sinus ostium and inserted 18Ϯ11 mm distally into the left atrium. The insulating compartment in which the connections traversed between the left atrium and the coronary sinus was mostly formed of adipose tissue. The valve of Vieussens was found in 6 hearts at a mean distance of 3.4Ϯ3.2 mm from the distal extremity of the coronary sinus muscle cuff. Conclusions-In the human heart, a consistent but morphologically variable left atrial coronary sinus myocardial connection was found. This emphasizes the need for surgical dissection or catheter ablation in or around the coronary sinus to eliminate these connections. (Circulation. 2000;101:647-652.)

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The Development of the Cardiac Specialized Tissue

Cited by 42 publications

References 0 publications

Morphological and electrophysiological correlates of atrioventricular nodal response to increased vagal activity.

Morphological and electrophysiological correlates of atrioventricular nodal response to increased vagal activity.

Cardiac Chamber Formation: Development, Genes, and Evolution

The Anatomic Basis of Connections Between the Coronary Sinus Musculature and the Left Atrium in Humans

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