The Cardiovascular System

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The Cardiovascular System
Page 330, 336,337, 338, 340
Dr. Vohra
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Develoment of the Heart
Introduction
The CVS is the 1st major system to function in
the embryo. The primordial heart vascular
system appear in the middle of the 3rd week The
heart starts to circulate blood at the beginning
of the 4th week can be visualized by
ultrasonography at this stage
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The CVS is derived mainly from

• Splanchnic mesoderm
• Paraxial lateral mesoderm
• Neural crest cells
• Angiogenesis Development of blood vessels

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Early Development of the Heart
Derived from cardiogenic mesoderm In the early
stages (3rd week) paired endothelial strands are
formed called ANGIOBLASTIC CORDS (cardiac
primordia)
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These cord like strands canalized (obtain lumen)
to form two thin walled endothelial heart tubes
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Late in the 3rd week due to the lateral
embryonic folding the endocardial come closure
fuse to form a single heart tube
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Further Development of the Heart
The primordium of the heart first evident at 18th
day
Cardiogenic area
Angioblastic cords
Thin walled
Two endocardial heart tubes
Embryonic folding
Single heart tube
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Cardiac Jelly
External layer of embryonic heart is formed from
splanchnic mesoderm which give rise to primitive
myocardium, that is surrounded by gelatinous CT
that will form the epicardium. (visceral
pericardium)
Dr. Vohra