Vascular Embryology: Topic 7 Flashcards
Vascular development occurs by what two mechanisms?
Vasculogenesis
Angiogenesis
Vasculogenesis
Coalescence of angioblasts
i.e. Major vessels such as the dorsal aorta and cardinal veins
Angiogenesis
Vessels sprout from existing vessels
I.e. remainder of vascular system
What leads to enlargement of some vessels while other vessels are obliterated?
Preferential flow related to the development of organs
How does enlargement of vessels occur?
By way of fusion with smaller vessels and partly by enlargement of individual capillary beds
What are the major arterial conduits in the early embryo?
Dorsal aortas
What is simply a continuation of the endocardial tubes?
Dorsal aortas
Where do dorsal aortas arise from?
Aortic sac (distal most part of the truncus arteriosus)
What establishes the first pair of aortic arches?
Because of the changing position of the developing heart tube and pericardium, the cranial portions of the dorsal aortas come to describe an arc on both sides of the foregut
How many pairs of aortic arches are present at some point during development?
6 pairs
What is the only transient aortic arch?
5th aortic arch
What is notable about the 5th aortic arch?
It never forms or forms incompletely and regresses
How are the aortic arches numbered?
I, II, III, IV, VI
What happens to the arches as they develop?
Some become modified and others regress
At day 27, the aortic arch I has largely disappeared. Part of it remains and becomes what?
Maxillary Artery
Remnant of Arch II becomes what?
Stapedial Artery
Aortic arches IV and VI are being formed as what?
Ventral and dorsal sprouts
What does Arch III form?
Common carotid artery and first part of the internal carotid artery
What does Arch IV become?
Left Arch IV
Right Arch IV
Left Arch IV
part of the aortic arch between LCC and L. Subclavian
Right Arch IV
Proximal R. Subclavian
Aortic Sac becomes…
Ascending Aorta
Aortic Arch
Brachiocephalic Artery
First Arches become…
Maxillary Artery (portion)
Second Arches become…
Stapedial Artery (portion)
Third Arches become…
Carotid Arteries
Fourth Arches become….
Right-Proximal Right Subclavian Artery
Left- Aortic arch segment between left carotid and left subclavian artery
Fifth Arches become…
Transient and never well-developed
Sixth ARches become
Right- Proximal (proximal R pulmonary arterY)/Distal (distal portion disappears)
Left-Proximal(proximal left pulmonary artery) / Distal (ductus arteriosus)
Right Dorsal Aorta becomes…
portion becomes the right subclavian
Left Dorsal Aorta becomes…
Distal aortic arch and descending aorta
Right Intersegmental Artery becomes…
part of right subclavian artery
Left Intersegmental Artery becomes….
left subclavian artery
What is the major point of entry into the common atria?
Sinus venosus
Sinus venosus remains paired until the embryo is how many mm, even after the endocardial tubes fuse?
4 mm
In a 4mm embryo, there is a distinguishable …… (3)
Central (unpaired) portion
Transverse portion
Right and left sinus horns
Mid 4th week, the sinus venosus receives blood form where?
Right and left sinus horns
Each horn receives blood from what 3 veins?
Vitelline vein
Umbilical vein
Common Cardinal Vein
AT what week does the obliteration of the right umbilical vein and left vitelline vein occur?
Occurs 5th week
At what week does the left common cardinal vein become obliterated?
Week 10
What is the entrance to the common atrium called?
Sinuatrial orifice
Sinuatrial orifice is flanked on each side by what?
Valvular folds
Sinus venosus receives 3 pairs of veins called wha/
Vitelline veins
Umbilical veins
Common cardinal veins
Vitelline veins
carry blood from the yolk sac to the sinus venosus; enter the sinus venosus
Umbilical veins
originate in the chorionic villi and carry oxygenated blood to the embryo; enters the sinus venosus lateral to the vitelline veins
Common cardinal veins
drain the body of the embryo
In the primitive heart (tube), the left and right sinus horns drain into what?
Central sinoatrial orifice
Vitelline veins give rise to what veins?
Hepatic veins
Umbilical venous system persists as what in the term fetus?
Umbilical vein
Cardinal venous system
enter the sinus venosus lateral/superior to the umbilical veins, forms a large complex network of veins throughout the body
Subcardinohepatic anastomosis was once…
Right umbilical vein
What will eventually become the coronary sinus?
Left sinus horn
