Topic 7: Vascular embryology Flashcards
Vascular development Occurs by 2 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
The early embryonic vascular system is a complex network, preferential flow related to the development of organs leads to enlargement of some vessels while other vessels are obliterated. This enlargement of vessels is by way of?
fusion with smaller vessels and partly by enlargement of individual capillary beds
The major arterial conduits in the early embryo are the?
dorsal aortas
- Simply a continuation of the endocardial tubes
- Arise from the Aortic Sac (Distal most part of the truncus arteriosus)
Dorsal Aortas: continuation of? arise from?
- Simply a continuation of the endocardial tubes
* Arise from the Aortic Sac (Distal most part of the truncus arteriosus)
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, establishing what?
first pair of aortic arches
There are how many of aortic arches present at some point during development? and which is transient?
six pairs
but the 5th aortic arch is only transient.
5th Aortic Arch never forms or forms incompletely and regresses
Aortic Sac becomes what?
- Ascending Aorta
- Aortic Arch
- Brachiocephalic Artery
First Arches becomes what?
•Maxillary Artery (portion)
Second Arches becomes what?
•Stapedial Artery (portion)
Third Arches becomes what?
•Carotid Arteries
Fourth Arches becomes what?
- Right–Proximal Right Subclavian Artery
* Left–Aortic arch segment between left carotid and left subclavian artery
Fifth Arches becomes what?
•Transient and never well-developed
Sixth Arches becomes what?
- Right–
* Proximal-Proximal right pulmonary artery
* Distal-distal portion disappears - Left–
* Proximal–Proximal left pulmonary artery
* Distal–Ductus Arteriosus
Right Dorsal Aorta becomes what?
•Portion becomes the right subclavian
Left Dorsal Aorta becomes what?
•Distal aortic arch and descending aorta
Right Intersegmental Artery becomes what?
•Part of right subclavian artery
Left Intersegmental Artery becomes what?
•Left subclavian artery
3mm Embryo
The first pair of arches is large
•Second pair is just forming
•All the other arches develop from the region of what????
•Distally, the dorsal aortas fuse to form what???
the aortic sac
a single vessel
4mm Embryo, 27 days
Aortic arch I has largely disappeared
•Part of it remains-becomes what?
the Maxillary Artery
4mm Embryo, 27 days
Aortic arch II is regressing.
•Remnants of arch II–becomes what?
the Stapedial Artery
4mm Embryo, 27 days
Aortic arches IV and VI are being formed as ventral and dorsal sprouts.
•Aortic arch VI already has a sprouting branch of what??
the primitive pulmonary artery
4mm Embryo, 27 days
Aortic arch III is already ?
large and well developed
10mm Embryo 29 days
The first two aortic arches have___?
•Aortic arches III, IV, and VI are __?
disappeared
quite large.
10mm Embryo 29 days
The truncoaortic sac has been divided so that Arch ___ is now continuous with the pulmonary trunk.
•Starting to lose ___?
arch VI
symmetry
The intersegmental arteries will be important in the formation of the ____ arteries
subclavian
14mm Embryo
The symmetrical pattern is largely gone
•There is further division of what?
•Arch III forms the common carotid artery and first part of the ______
aorta and pulmonary artery.
internal carotid artery
14mm Embryo
The symmetrical pattern is largely gone
•There is further division of the aorta and pulmonary artery.
•Arch III forms the ________
common carotid artery and first part of the internal carotid artery
14mm Embryo
Arch IV stays on each side but becomes different structures.
•Left Arch IV–part of what????
•Right Arch IV–location???
part of Aortic arch between LCC and L. Subclavian
Proximal R. Subclavian
14mm Embryo
The dorsal portion of the right arch VI has disappeared and the left arch VI will become what??
ductus arteriosus
14mm Embryo
Arch VI aka. ?
Pulmonary Arch
14mm Embryo
Notice the intersegmental arteries have migrated upward to become the what?
subclavian arteries
17mm Embryo
A portion of the vessel that was formerly the right dorsal aorta disappears.
•Proximal portion persists and becomes what??
right subclavian artery
At birth, the distal part of the left sixth aortic arch(aka the ____ ) normally obliterates and becomes the ? ligamentum arteriosum.
•The adult aortic arch system is now established
(the ductus arteriosus)
ligamentum arteriosum.
Arch 1 – arterial derivatives
Maxillary Arteries
Arch 2 - arterial derivatives
Hyoid and stapedial arteries
Arch 3 - arterial derivatives
common carotid and first part of the internal carotid arteries
Arch 4 - left side
Arch of the aorta from the left common carotid to the left subclavian arteries
Arch 4 - right side
Right subclavian artery (proximal portion)
Arch 6 - left side
Left pulmonary artery and ductus arteriosus
Arch 6 - right side
right pulmonary artery
The sinus venosus is the major point of entry into what ??
•Remains paired until the embryo is ___
•Even after the endocardial tubes fuse
common atria.
4mm
Sinus Venosus
In a 4 mm embryo, there are 3 distinguishable portions ?
- Central (unpaired) portion,
- Transverse portion
- Right and left sinus horns
Mid 4th week the sinus venosus receives blood from where? •Each horn receives blood from 3 veins •Vitelline vein •Umbilical vein •Common Cardinal vein
right and left sinus horns
Mid 4th week the sinus venosus receives blood from right and left sinus horns
•Each horn receives blood from what 3 veins?
- Vitelline vein
- Umbilical vein
- Common Cardinal vein
Communication between sinus and atrium is wide open
•Communication will eventually shift to the right
•Caused by what????
shift in blood in venous system
•Occurs at about 4-5 weeks
Communication between sinus and atrium is wide open
•Communication will eventually shift to the right
•Caused by shift in blood in venous system
•Occurs at what time frame???
about 4-5 weeks
Communication between sinus and atrium is wide open
•Communication will eventually shift where??
to the right
•Caused by shift in blood in venous system
•Occurs at about 4-5 weeks
Sinus Venosus
Obliteration of the right umbilical vein and left
vitelline vein
•Occurs what week??
5th week
•Left sinus horn loses importance
At week 10 the ________ become obliterated
•All that remains of the left sinus horn is the oblique vein of the left atrium and the coronary sinus
left common cardinal vein
At week 10 the left common cardinal vein become obliterated
•All that remains of the left sinus horn is the what 2 things??
oblique vein of the left atrium and the coronary sinus
Right Sinus horn
•Shunt of blood left to right enlarges right sinus horn
•Right horn and vein are the only communication between the what two areas??
original sinus venosus and the atrium
•Forms the smooth walled part of the right atrium
Sinuatrial orifice is the entrance to what?
to the common atrium, and it is flanked on each side by valvular folds.
Sinuatrial orifice has Right and left venous valves
•Left venous valve fuses with_____
•Superior part of the right venous valve ____
•Inferior part of the right venous valve becomes the valve of ?
the atrial septum
disappears
inferior vena cava and the valve of the coronary sinus.
Sinuatrial orifice has Right and left venous valves
left venous valve fuses with?
the atrial septum
Sinuatrial orifice has Right and left venous valves
Superior part of the right venous valve does what?
disappears
Sinuatrial orifice has Right and left venous valves
Inferior part of the right venous valve becomes the valve of what 2 structures?
inferior vena cava and the valve of the coronary sinus.
Vitelline veins carry blood where?
Carry blood from the yolk sac to the
sinus venosus
(sinus venosus receives these veins)
Umbilical veins - start and end?
Originate in the chorionic villi and carry
oxygenated blood to the embryo
(sinus venosus receives these veins)
Common cardinal veins do what?
Drain the body of the embryo
sinus venosus receives these veins
In the primitive heart (tube), the left and right sinus horns drain into ?
a central sinoatrial orifice
In the early stages of vascular development, there are three main groups of veins?
- Vitelline venous system
- Umbilical venous system
- Cardinal venous system
•Vitelline venous system - enters? gives rise to?
Enters the sinus venosus
•Gives rise to the hepatic veins
•Umbilical venous system - enters? persists as?
- Enter the sinus venosus lateral to the vitelline veins.
* Persists as the umbilical vein in the term fetus.
•Cardinal venous system - enters? forms?
- Enters the sinus venosus lateral/superior to the umbilical veins
- Forms a large complex network of veins throughout the body
the subcardinohepatic anastomosis, was once what?
10mm Embryo
right umbilical vein
In a 14mm embryo the left sinus horn has separated from the right and will eventually become what?
the coronary sinus
In a 14mm embryo, the right side of the subcardinal venous system is developing into the principle venous channels to the heart from where?
the lower body
17mm Embryo
The upper limbs are now drained by veins which empty into the anterior cardinal veins.
•The major portions of the posterior cardinal veins have disappeared
•There is even greater demand on which vein???
the right subcardinal vein
24mm Embryo
The anterior cardinal veins now have a channel between them – which is what?.
•These cardinal veins will drain the entire head and upper extremities
the left brachiocephalic vein
24mm Embryo
The anterior cardinal veins now have a channel between them (L brachiocephalic vein)
•These cardinal veins will drain what part of the body??
the entire head and upper extremities
24mm Embryo
The subcardinal veins have completely fused
•Make up a large portion of what will become the ______?
•There are now clear venous channels to the kidneys and adrenal glands.
inferior vena cava
