Document Detail

How does the tubular embryonic heart work? Looking for the physical mechanism generating unidirectional blood flow in the valveless embryonic heart tube.
MedLine Citation:
PMID:  20235196     Owner:  NLM     Status:  MEDLINE    
The heart is the first organ to function in vertebrate embryos. The human heart, for example, starts beating around the 21st embryonic day. During the initial phase of its pumping action, the embryonic heart is seen as a pulsating blood vessel that is built up by (1) an inner endothelial tube lacking valves, (2) a middle layer of extracellular matrix, and (3) an outer myocardial tube. Despite the absence of valves, this tubular heart generates unidirectional blood flow. This fact poses the question how it works. Visual examination of the pulsating embryonic heart tube shows that its pumping action is characterized by traveling mechanical waves sweeping from its venous to its arterial end. These traveling waves were traditionally described as myocardial peristaltic waves. It has, therefore, been speculated that the tubular embryonic heart works as a technical peristaltic pump. Recent hemodynamic data from living embryos, however, have shown that the pumping function of the embryonic heart tube differs in several respects from that of a technical peristaltic pump. Some of these data suggest that embryonic heart tubes work as valveless "Liebau pumps." In the present study, a review is given on the evolution of the two above-mentioned theories of early cardiac pumping mechanics. We discuss pros and cons for both of these theories. We show that the tubular embryonic heart works neither as a technical peristaltic pump nor as a classic Liebau pump. The question regarding how the embryonic heart tube works still awaits an answer.
Jörg Männer; Armin Wessel; T Mesud Yelbuz
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Developmental dynamics : an official publication of the American Association of Anatomists     Volume:  239     ISSN:  1097-0177     ISO Abbreviation:  Dev. Dyn.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-29     Completed Date:  2010-08-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9201927     Medline TA:  Dev Dyn     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1035-46     Citation Subset:  IM    
Department of Anatomy and Cell Biology, Georg-August-University of Göttingen, D-37075 Göttingen, Germany.
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MeSH Terms
Blood Flow Velocity / physiology
Coronary Circulation / physiology*
Embryonic Development / physiology
Heart / embryology*,  physiology*
Heart Valves / embryology,  physiology
Models, Biological
Models, Cardiovascular
Pulsatile Flow / physiology

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