cvs+embryology+part+i+ +a2+students+only
DESCRIPTION
For study purpose only.TRANSCRIPT
EMBRYOLOGY CVS – PART I
CVS Embryology 1
• 1st system to function in embryo
• Circulation of blood : 3rd week
• Derived from mesenchyme
EMBRYOLOGY : CVS
CVS Embryology 1
EMBRYOLOGY : CVS
CVS Embryology 1
• Mesenchymal cells in splanchnic mesoderm proliferate &
form cell clusters : Angiogenic clusters
EMBRYOLOGY : CVS
• Angiogenic cell cluster
EMBRYOLOGY : CVS
CVS Embryology 1
• Angiogenic clusters on lateral side then
spread rapidly in cephalic direction
caudal
cephalic
EMBRYOLOGY : CVS
CVS Embryology 1
• Angiogenic clusters form horseshoe shaped plexus of blood vessels
• Anterior central part of plexus : Cardiogenic area
EMBRYOLOGY : CVS
CVS Embryology 1
Heart Development
• Develops from splanchnic mesenchyme in cardiogenic area.
EMBRYOLOGY : CVS
Cardiogenic area
EMBRYOLOGY : CVS
EMBRYOLOGY : CVS
The Pericardial cavity
CVS Embryology 1
CVS EMBRYOLOGY
Bilateral cardiogenic cords:
• Formed from mesenchyme
• Cords canalized
• Form paired endocardial heart tubes
• Endocardial tubes fuse into single heart tube forming primitive heart
CVS EMBRYOLOGY
CVS Embryology 1
Fusion of primitive heart tubes
CVS EMBRYOLOGY
PRIMITIVE HEART
• Heart tube elongates & bends
• Cephalic portion : bend in ventral & caudal direction & to right
• Caudal portion : bends to left
CVS Embryology 1
• Bending creates cardiac loop
PRIMITIVE HEART
CVS Embryology 1
• The cardiac loop
EMBRYOLOGY : CVS
EMBRYOLOGY : CVS
Future heart develops dilatations & constrictions : results in 4 chambers:
• sinus venosus
• primordial atrium
• primodial ventricle
• bulbus cordis
CVS Embryology 1
ACV: Anterior cardinal vein
PCV: Posterior cardinal vein
UV : Umbilical vein
VIT: Vitelline vein
EMBRYOLOGY : CVS Sinus Venosus
• Maintain paired condition longer
than any other portion of heart
tube
• Each horn receives the vitelline v,
umbilical v, common cardinal v
CVS Embryology 1
Sinus venosus receives:
• umbilical veins from the chorion.
• vitelline veins from the yolk sac
• common cardinal veins from the embryo.
CVS Embryology 1
EMBRYOLOGY : CVS Sinus Venosus
EMBRYOLOGY : CVS Sinus Venosus
Inferior portion of right sinus
develops into 2 parts:
• Valve of inferior vena cava
• Valve of coronary sinus
CVS Embryology 1
EMBRYOLOGY : CVS Sinus Venosus
• Wk 4 consist of small transverse
portion & L & R sinus horns
CVS Embryology 1
EMBRYOLOGY : CVS Sinus Venosus
EMBRYOLOGY : CVS Sinus Venosus
EMBRYOLOGY : CVS Sinus Venosus
• At 1st communication between sinus & atrium is wide
• With obliteration of the left umbilical vein , the left sinus
horn loses its importance
CVS Embryology 1
• develops a left horn which becomes the coronary sinus & a right horn which will be incorporated
into right atrium
EMBRYOLOGY : CVS Sinus Venosus
CVS Embryology 1
EMBRYOLOGY : CVS Sinus Venosus
Remnant of the left sinus venosus :
• Oblique vein of left atrium
• Coronary sinus
CVS Embryology 1
• Bulbus cordis & ventricle grow faster
EMBRYOLOGY : CVS
CVS Embryology 1
• Heart bends upon
itself, forming a
bulboventricular loop
EMBRYOLOGY : CVS
CVS Embryology 1
• bulboventricular loop
EMBRYOLOGY : CVS
CVS Embryology 1
• Intro to atrium & sinus
• Atrium & sinus venosus come to lie dorsal to bulbus cordis, truncus arteriosus &
ventricle
• At the same time, heart invaginates into pericardial cavity
• Dorsal mesocardium which attaches it to dorsal wall of pericardial cavity degenerates &
forms tranverse pericardial sinus
EMBRYOLOGY : CVS
CVS Embryology 1
Truncus Arteriosus
• Continues caudally with bulbus
cordis
• Enlarges cranially to form aortic sac
from which aortic arches arise
CVS Embryology 1
EMBRYOLOGY : CVS Truncus Arteriosus
• Enlarges cranially to form aortic sac
from which aortic arches arise
EMBRYOLOGY : CVS Truncus Arteriosus
EMBRYOLOGY : CVS THE ATRIA
Fate of adult Left Atrium
• Formed by incorporation of primitive pulmonary veins
• As atrium enlarges, parts of vein & its branches absorbed
CVS Embryology 1
• Primitive pulmonary vein & its 4 main branches become partially incorporated into left atrium = 4
pulmonary veins.
EMBRYOLOGY : CVS
CVS Embryology 1
Result
• 4 pulmonary veins entering adult left atrium
• Smooth walled part of left atrium derived from absorbed pulmonary vein tissue
• Left auricle derived from primitive atrium
EMBRYOLOGY : CVS
CVS Embryology 1
EMBRYOLOGY : CVS
Development of the smooth-walled portions of the right and left atrium.
Both the wall of the right sinus horn (blue) and the pulmonary veins (red) are
incorporated into the heart to form the smooth-walled parts of the atria.
EMBRYOLOGY : CVS
Cardiac septation
End of 4th wk, 2 mesenchymal cushions, the atrioventricular endocardial cushions,
appear at the superior and inferior borders of the atrioventricular canal
In addition, 2 lateral atrioventricular cushions appear on the right and left borders of the canal
EMBRYOLOGY : CVS Cardiac septation
EMBRYOLOGY : CVS
Cardiac septation
EMBRYOLOGY : CVS
CVS Embryology 1
• End of 4th week, sickle shaped crest grows from roof of atrium : Septum
Primum
• Opening between septum primum & endocardial cushion: ostium primum
• Limbs of septum extend in direction of endocardial cushions
EMBRYOLOGY : CVS
CVS Embryology 1
EMBRYOLOGY : CVS
• Crescent shaped fold : septum secundum
• Never forms complete partition in atrial cavity
• Free concave edge overlaps ostium secundum
CVS Embryology 1
EMBRYOLOGY : CVS
• Opening left by septum secundum : Oval foramen
CVS Embryology 1
• Before birth foramen ovale allows blood to pass from right atrium into left atrium; reflux is
prevented by the valve. After birth foramen ovale normally closes by fusion of septum primum &
septum secundum.
EMBRYOLOGY : CVS
CVS Embryology 1
EMBRYOLOGY : CVS
CVS Embryology 1
• During week 5, bulbus cordis & truncus arteriosus become divided by an aorticopulmonary
septum into pulmonary trunk & aorta.
EMBRYOLOGY : CVS
• During week 5, bulbus cordis & truncus arteriosus become divided by an aorticopulmonary
septum into pulmonary trunk & aorta.
EMBRYOLOGY : CVS
• Ventricles become partitioned by a crescentic fold which is open cranially until end of week 7.
EMBRYOLOGY : CVS
CVS Embryology 1
EMBRYOLOGY : CVS
CVS Embryology 1
• Primitive ventricle : give rise to most of left ventricle
EMBRYOLOGY : CVS
• Bulbus cordis : forms most of right ventricle
CVS Embryology 1