Vascular Embryology Flashcards
How do vessels enlarge?
Fusion with smaller vessels
Enlargement of individual capillary beds
2 mechanisms of vascular development
- Vasculogenesis: coalescence of angioblasts (Major vessels such as dorsal aorta and cardinal veins)
- Angiogenesis: vessels sprout from existing vessels (remainder of vascular system)
Major arterial conduits in the early embryo
Dorsal aortas (continuation of endocardial tubes, arose from aortic sac)
Formation of the first pair of aortic arches
Cranial portions of the dorsal aortas create an arc on both sides of the foregut due to movement of the developing heart tube and pericardium
3mm embryo
1st pair of aortic arches large
2nd pair just forming
All other arches form from aortic sac
Aortic arch one becomes
Maxillary artery
Aortic arch two becomes
Stapedial artery
Primitive pulmonary artery comes from which arch?
Aortic arch 6
What happens when the turn aortic sac divides?
Aortic arch 6 is now continuous with the pulmonary trunk
Starting to lose symmetry
Inter segmental arteries are important in the formation of?
Subclavian arteries
Aortic arch 3 forms:
Common carotid artery and first part of internal carotid
Aortic arch 4 forms:
Left side: aortic arch between L common carotid and L subclavian
Right side: proximal right subclavian
Another name for arch 6
Pulmonary arch
Aortic arch 6 becomes:
Dorsal portion of right arch 6 disappears
Proximal part of right arch becomes right pulmonary artery
Distal Left arch becomes ductus arteriosus
Proximal left arch becomes proximal left pulmonary artery
Ductus arteriosus at birth
Normally obliterates, forming ligamentum arteriosum
Aortic sac becomes
Ascending aorta
Aortic arch
Brachiocephalic artery
Right dorsal aorta becomes
Right subclavian
Left dorsal aorta becomes
Distal aortic arch and descending aorta
Right intersegmental artery becomes:
Right subclavian
Left intersegmental artery becomes:
Left subclavian
Major point of entry into common atria
Sinus venosus
In 4mm embryo, 3 distinguishable parts of sinus venosus
Central (unpaired) portion
Transverse portion
Right and left sinus horns
Blood supply to the sinus venosus, week 4:
Sinus venosus receives blood via right and left horns
Each horn receives blood from vitelline, umbilical, and common cardinal veins
Communication between the sinus and atrium is initially wide open, what causes a shift from this?
Shifts to the right due to shift in blood in venous system
Occurs at about 4-5 weeks
Fate of right umbilical vein, left vitelline vein, and left common cardinal vein
Obliterated week 5: right umbilical and left vitelline veins
-Left horn no longer important
Obliterated week 10: left common cardinal vein
-all that remains of left sinus horn is oblique vein of the LA and the coronary sinus
Only communication between the original sinus venosus and the atrium?
Right sinus horn
- shunts blood left to right, so right sinus horn enlarges
- forms the smooth wall part of the right atrium
Left sinus horn and right sinus horn become?
Left sinus horn: oblique vein of LA and coronary sinus
Right sinus horn: smooth wall of RA
Valvular fold on either side of the sinuatrial orifice:
Left venous valve: fuses with atrial septum
Superior right venous valve: disappears
Inferior right venous valve: becomes valve of IVC and valve of right coronary sinus
Function of vitelline veins:
Carry blood from yolk sac to sinus venosus
Function of umbilical vein:
Originate in chorionic villi and carry OXYGENATED blood to the embryo
Function of common cardinal veins:
Drain the body of the embryo
In primitive heart tube, left and right sinus horns drain into?
Central sinoatrial orifice
Where does the vitelline venous system enter and what does it give rise to?
Enters sinus venosus
Gives rise to hepatic veins
Were does the umbilical venous system enter and what does it give rise to?
Enters sinus venosus lateral to vitelline veins
Persists as umbilical vein in the fetus
Where does the cardinal venous system enter and what does it give rise to?
Enters sinus venosus lateral/superior to the umbilical veins
Forms a large complex network of veins throughout body
Fate of left vitelline vein
Disappears
Fate of right vitelline vein
Becomes hepatic veins and all other veins of hepatic portal system
Fate of left umbilical vein
Joins hepatic system, bit still persists in fetus as umbilical vein
Fate of right umbilical vein
Subcardinohepatic anastomosis
What does the left sinus horn become?
Coronary sinus
Right side of the subcardinal venous system develops into?
Principle venous channels to the heart from lower body
Anterior and posterior cardinal veins:
Anterior drain the upper limbs
Posterior mostly disappear (so even greater demand on right subclavian vein)
Chamber between the anterior cardinal veins:
Brachiocephalic vein
Drains entire head and upper extremities
Sub cardinal veins completely fuse to become:
IVC
