Great Arteries and Veins Embryology Flashcards
What is vasculogenesis?
formation of new vascular channels by assembly of angioblasts
from mesoderm
What is angiogenesis?
development of blood vessels from pre-existing vessels
What is arteriogenesis?
remodeling of existing arteries in response to changes
What does vasculogenesis begin?
end of third week
What is the general sequence of cell changes during vasculogenesis?
undifferentiated mesoderm –> hemangioblasts –> form HSCs and endothelial precursors –> blood islands form–> capillaries w/ primitive erythrocytes
Where do the channels w/ hematopoietic stem cells form?
in extraembryonic splanchnic mesoderm around umbilical vessel
AGM
What is a capillary hemangioma?
excessive growth of small capillary networks
cherry angiomas
What is a cavernous hemangioma?
proliferation of large dilated vascular chanels
What are hemangiomas of infancy?
benign tumors affecting up to 10% caucasian infants
due to abnormalities in vasculogenesis
consist of many endothelial cells
What do you see in the great veins in the fourth week?
first aortic arch formed –> supplies first pharyngeal arch
paired dorsal aorta that fuse in abdomen
What are the branches off the fused dorsal aorta?
ventral segmental arteries –> gut
lateral segmental arteries –> kidneys and gonads
dorsal intersegmental arteries –> supply derivatives of somites
What type of embryologic tissues do the ventral segmental arteries supply?
splanchnic layer of lateral plate mesoderm and endoderm (gut)
what do the dorsal intersegmental arteries become?
intercostal As
When does the formation of aortic arches 2-6 occur?
days 26-32
How in general do the aortic arches form?
one after the other, with the previous arch degenerating once the next one forms
When is the formation of the aortic arches completed?
days 32-37
What are the derivatives of the 1st pharyngeal arch?
external carotid, maxillary
What are the derivatives of the 2nd pharyngeal arch?
stems of stapedial arteries
What are the derivatives of the aortic sac?
brachiocephalic artery
base of arch of aorta
What are the derivatives of the 3rd pharyngeal arch?
common carotid
internal carotid
What are the derivatives of the 4th pharyngeal arch?
left: medial portion of arch of aorta
right: proximal Rt subclavian A
What are the derivatives of the 6th pharyngeal arch?
pulmonary arteries (lungs and larynx)
Left: distal ductus arteriosus
Right: distal degenerates
What are the derivatives of the 7th pharyngeal arch?
right: distal part of right subclavian
left: entire left subclavian artery
What are the derivatives of the dorsal aorta?
right: portion of right subclavian A
left: descending aorta
How does the development of the arteries contribute to the position of recurrent laryngeal nerves?
Distal half of R 6th arch degrades , so right recurrent goes back up earlier
L distal 6th arch turns into ductus arteriosus –> left recurrent laryngeal N continues down and wraps around it
What is the ductus venosus?
V that allows placental blood to bypass liver and go straight from umbilical vein to inferior vena cava
Where does oxygen rich fetal blood typically go once it reaches the R atrium?
likes to go straight to L atrium –> L ventricle –> aorta
some blood will go normal adult path and then go from pulmonary A to aorta –> blood from this route is less oxygenated and goes to lower extremity
What part of the body gets the most oxygen rich blood?
the brain
When should the ductus arteriosus close?
72 hours after birth
What causes the foramen ovale to close after birth?
Higher pressure in the L atrium
What happens at birth in the lungs?
decrease in pulmonary vascular resistance
increase in pulmonary blood flow
thinning of walls of pulmonary arteries
What happens to the ductus venosus after birth?
spincter constricts –> turns into ligamentum venosum
What causes the sphincter of ductus venosus to close after birth?
increased O2 –> decreased prostaglandins –> more bradykinin –> smooth muscle contracts
What is coarctation of the aorta?
What are the two types?
constriction of the aorta
preductal
postductal
What happens in postductal coarctation of the aorta?
fetus will develop collateral circulation to the body
Clinically, what would you see in a baby w/ coarctation of the aorta?
How would you treat it?
higher pulses and BP in upper limbs
lower bp and weaker pulse in lower limbs
give prostaglandins to help open
What causes coarctation of the aorta?
we think: smooth muscle abnormally migrates to aorta –> closes it off
OR: abnormal remodeling of vasculature
How does a double aortic arch occur?
Where do you find it?
persistence of the distal portion of the right dorsal aorta
forms a vascular ring around the trachea and esophagus
What do pts present with if they have a double aortic arch?
trouble breathing, stridor
esophageal complaints also
(due to aortic ring around these two structures that can compress them)
What causes an interrupted aortic arch?
both right and left 4th aortic arches are obliterated –> distal R aorta is retained
What do babies present w/ if they have an interrupted aortic arch?
weakness, fatigue, poor feeding
rapid breathing and heart rate
low O2 levels especially in LE
DiGeorge’ syndrome is associated with what cardiac abnormality?
interrupted aortic arch
What happens in abnormal origin of right subclavian artery?
R 4th aortic arch and proximal part of the R dorsal aorta obliterate –> subclavian arises from 7th intersegmental A and distal part of R dorsal aorta
ends up behind esophagus and trachea
How does a right aortic arch occur?
L fourth arch and L dorsal aorta are obliterated and replaced by the corresponding vessels on the right side
Clinically, what can affect swallowing in right aortic arch?
if ligamentum arteriosum lies on the L side and passes behind esophagus
What does the right horn of the sinus venosus give rise to?
sinus venerum and crista terminalis of R atrium
What does the L horn of the sinus venosus give rise to?
coronary sinus
When does veinous flow to the heart remodeling occur?
weeks 4-8
What happens to the vitelline veins proximal to the heart?
Right: persists
Left: degenerates
What happens to the the vitelline veins in the liver?
right –> hepatic vein
R and L –> form portal vein from gut
What happens to the Rt umbilical vein?
degenerates entirely
What happens to the L umbilical vein?
proximal degenerates
anastomoses w/ ductus venosus
distal persists in embryo for placental return
What happens to the anterior cardinal Vs?
right –> internal jugular and superior vena cava
Left –> left brachiocephalic V
What happens to the posterior cardinal Vs?
drains from body wall
degenerates except for root of azygos and common iliac Vs
replaced by subcardinal and supracardinal Vs
What happens in Left superior vena cava?
persistence of left anterior cardinal v and obliteration of the common cardinal and proximal part of anterior cardinal vs on the R
What happens in double superior vena cava?
L anterior cardinal V persists
L brachiocephalic vein fails to form
What does the hepatic segment of the inferior vena cava arise from?
vitelline/hepatic veins and sinuses
What does the prerenal inferior vena cava arise from?
Rt SUBcardinal V
What does the renal vena cava arise from?
subcardinal-supracardinal anastomosis
What does the postrenal vena cava arise from?
Rt SUPRAcardinal V
What is the round ligamentum teres/round ligament of the liver?
remnant of the umbilical vein
How does a fetus compensate for a preductal coarctation?
can bypass through the ductus arteriosus (but this won’t work after birth when this closes)
