cardiovascular embryology Flashcards
why does the very early embryo have no need of a CV system
meets all nutritional needs by simple diffusion
when does the rudimentary CV system begin to develop
once the embryo reaches the 3 layer stage
what is three layer stage
inner endoderm
mesoderm
middle and outer ectoderm
what do the cells in the splanchnic mesoderm form in haemangioblast cells
blood islands
what do blood islands stimulate
surrounding mesenchymal cells
what do blood islands form surrounding mesenchymal cells
endothelial and smooth muscle cells which form walls around the blood islands.
how is dorsal aortae formed in the dorsal mesenchyme
small vessels ( mesenchymal cells) coalesce and bud to form larger communicating vessels.
what leads to the formation of left and right coeloms
cavitation of the mesoderm
what does fusing of left and right coeloms to the developing neural plate form
one horseshoe shaped coelomic cavity
how does the foetus receive oxygenated blood
from the allantois via the umbilical veins
how does the foetus receive nutrition
yolk sac via the vitelline veins
is the pulmonary system functional in the foetus
no
what forms the cardiogenic plate ventral to the forming dorsal aorta and coelom
mesoderm
what does the cardiogenic plate become and what does it initially have
endocardial tube which initially has a left and right limb
what does mesoderm around the endocardial tubes form
a myoepicardial mantle
what does the myoepicardial mantle give and develop into
contractile ability to the endocardial tube and develops into the myocardium
movement of development of the heart in the embryo
moves caudally from the head as the embryo matures to end up in the thorax
what is the effect on the endocardial tube as the embryo folds
brings the endocardial tube dorsal to the coelom and the two limbs coalesce to form the primitive heart which functions as a single pump
what do the vitelline veins form
yolk sac anastomose to the cardiac tube
what does the joining of dorsal aortae to the endocardial tube form
first aortic arches
what does the fusing of the aorta caudally to the developing heart form
one common aorta
what does further folding of the embryo cause
changes cardiac tube to an s shaped structure consisting of 5 portions
what are the 5 portions of the s shaped structure
cranial to caudal:
truncus arteriosus
bulbus cordis
ventricle
atrium
sinus venosus
how is blood pumped into the circulation from the sinus venosus by
truncus arteriosus
what veins does the sinus venous receive blood via
umbilical
cardinal
vitelline
what does the sinus venosus become
part of the right atrium
what does the foetal atrium develop into
left and right atrial appendages
what does the foetal ventricle become
left ventricle
what does the bulbus cordis develop into
right ventricle
what does the truncus arteriosus pump blood out into
aortic arches
what does the truncus arteriosus divide to form
aorta
pulmonary arteries
what does the visceral pericardium form
epicardium of the heart wall
what develops from mesenchymal cells between the endocardium and myocardium in the area between the single atrium and ventricle
endocardial cushions
what does the fusing of endocardial cushions form and what does it do
septum intermedium
separates the AV canal into a left and right AV canal
what is the name of thee dividing septum that grows down from the dorsal atrial wall towards the endocardial cushions that divides the atrium in left and right atrium
septum primum
what is the name of the channel of communication that remains between left and right atria
foramen primum
what forms before the foramen primum eventually closes
foramen secundum
how does the foramen secundum form
programmed cell death (apoptosis) in the dorsal part of the septum
what is the second septum that grows down to the right of the septum primum
septum secundum
what is the foramen ovale
communication between atria via the aperture in the septum secundum and the foramen secundum.
what is the septum secundum also known as due to its dividing function
crista dividens
what forms when the dilated section of the bulbus cordis joins with the embryonic ventricle
single common ventricle
what does the non-dilated portion of the bulbus cordis become
conus cordis
what closes the interventricular foramen
differential cellular proliferation
what forms the primordial ventricular septum
groove visible on the outside of the heart between the bulbus and the foetal ventricle
what does the bulbus become
right ventricle
what does the foetal ventricle become
left ventricle
how does the ventricles grow
by peripheral growth and internal cavitation
how is chordae tendinae formed
replacement of the muscular tissue with connective tissue due to further differentiation
what do chordae tendinae attach to
papillary muscles - muscular projections
what must be separated to form the pulmonary trunk and aortic trunk
conus cordis (non dilated portion of the bulbus cordis) and the truncus arteriosus
what fuses to form the aortico-pulmonary septum
bulbar ridges (thickening along division between bulbus cordis and truncus arteriosus)
what does the sinus venosus become
sinoatrial node
what are the arteries that arise from the aorta and supply developing somites called
intersegmental
what is the point at which the dorsal aortae join the truncus arteriosus called
aortic sac
how many pairs of aortic arches form between the truncus arteriosus and the dorsal aortae
6
what is the connective tissue between the atria and ventricles
annulus fibrosis
where does the intersegmental arteries arise from and what do they supply
from the aorta and supplies the developing somites
what do the vitelline arteries supply
yolk sac
what do the umbilical arteries supply
allantois
what is the point at which the dorsal aortae join the truncus arteriosus called
aortic sac
what is the aortic sac surrounded by and what does it form
mesenchymal tissue that forms the pharyngeal arches
what are the aortic arches lateral to
developing foregut
what do the left and right aortic arches become
common carotid arteries
what derives from the third aortic arches
internal carotid arteries
what is the arch of the definitive aorta formed from
left 4th aortic arch artery, aortic sac and left dorsal aorta
where does the left subclavian artery arise from in dogs and pigs
directly from aortic arch
what forms the right subclavian artery
right 4th aortic arch artery
where does the left subclavian artery arise from in horses and cattle
brachiocephalic trunk
what forms the brachiocephalic trunk
portions of the left and right 3rd and 4th aortic arch arteries fuse with the aortic sac
what do the first 2 pairs of aortic arch arteries leave atrophy and what do they supply
small maxillary arteries and stapedial arteries which supply the middle ears
what happens to the 5th pair of aortic arch arteries
atrophies
what do the 6th aortic arch arteries form
pulmonary arteries
distal portion of the left 6th AAA forms the ductus arteriosus between the pulmonary artery and aorta.
where does coronary circulation arise from
endothelial sprouts near the aortic root and a sub-epicardial vessel plexus
where does the recurrent laryngeal branches of the vagus nerve pass
caudal to the 6th aaa
why is the left recurrent laryngeal nerve more likely to be damaged by stretching or turning of the neck
its fixed caudally at the ductus arteriosus
what are the 3 pairs of veins the early embryo has
vitelline veins
umbilical veins
cardinal veins
how is the liver sinusoids formed
vitelline veins pass through the septum transversum providing a venous plexus which is incorporated in the liver
what veins contribute to the development of the most cranial portion of the caudal vena cava
vitelline veins
function of the ductus venosus
diverts blood away from the hepatic sinusoids in the foetus
what does the left umbilical vein remnant become in the adult animal
round ligament of the liver
what do the cranial veins drain
head and neck
what do the caudal veins drain
body wall
what are the 3 veins that arise from the cranial cardinal veins
internal and external jugular veins
brachiocephalic veins
what arises from the right cranial cardinal vein after anastomosis with the left
cranial vena cava
what does the remaining part of the left cranial cardinal vein become
coronary sinus
what do the caudal cardinal veins give rise to and what do the drain
subcardinal veins
drain the developing kidney
what do supracardinal veins drain
dorsal body wall
what does the right supracardinal vein become
azygous vein
