Great Arteries and Veins Embryology

Question 1

What is vasculogenesis?

Answer 1

formation of new vascular channels by assembly of angioblasts
from mesoderm

Question 2

What is angiogenesis?

Answer 2

development of blood vessels from pre-existing vessels

Question 3

What is arteriogenesis?

Answer 3

remodeling of existing arteries in response to changes

Question 4

What does vasculogenesis begin?

Answer 4

end of third week

Question 5

What is the general sequence of cell changes during vasculogenesis?

Answer 5

undifferentiated mesoderm –> hemangioblasts –> form HSCs and endothelial precursors –> blood islands form–> capillaries w/ primitive erythrocytes

Question 6

Where do the channels w/ hematopoietic stem cells form?

Answer 6

in extraembryonic splanchnic mesoderm around umbilical vessel
AGM

Question 7

What is a capillary hemangioma?

Answer 7

excessive growth of small capillary networks

cherry angiomas

Question 8

What is a cavernous hemangioma?

Answer 8

proliferation of large dilated vascular chanels

Question 9

What are hemangiomas of infancy?

Answer 9

benign tumors affecting up to 10% caucasian infants
due to abnormalities in vasculogenesis
consist of many endothelial cells

Question 10

What do you see in the great veins in the fourth week?

Answer 10

first aortic arch formed –> supplies first pharyngeal arch

paired dorsal aorta that fuse in abdomen

Question 11

What are the branches off the fused dorsal aorta?

Answer 11

ventral segmental arteries –> gut
lateral segmental arteries –> kidneys and gonads
dorsal intersegmental arteries –> supply derivatives of somites

Question 12

What type of embryologic tissues do the ventral segmental arteries supply?

Answer 12

splanchnic layer of lateral plate mesoderm and endoderm (gut)

Question 13

what do the dorsal intersegmental arteries become?

Answer 13

intercostal As

Question 14

When does the formation of aortic arches 2-6 occur?

Answer 14

days 26-32

Question 15

How in general do the aortic arches form?

Answer 15

one after the other, with the previous arch degenerating once the next one forms

Question 16

When is the formation of the aortic arches completed?

Answer 16

days 32-37

Question 17

What are the derivatives of the 1st pharyngeal arch?

Answer 17

external carotid, maxillary

Question 18

What are the derivatives of the 2nd pharyngeal arch?

Answer 18

stems of stapedial arteries

Question 19

What are the derivatives of the aortic sac?

Answer 19

brachiocephalic artery

base of arch of aorta

Question 20

What are the derivatives of the 3rd pharyngeal arch?

Answer 20

common carotid

internal carotid

Question 21

What are the derivatives of the 4th pharyngeal arch?

Answer 21

left: medial portion of arch of aorta
right: proximal Rt subclavian A

Question 22

What are the derivatives of the 6th pharyngeal arch?

Answer 22

pulmonary arteries (lungs and larynx)
Left: distal ductus arteriosus
Right: distal degenerates

Question 23

What are the derivatives of the 7th pharyngeal arch?

Answer 23

right: distal part of right subclavian
left: entire left subclavian artery

Question 24

What are the derivatives of the dorsal aorta?

Answer 24

right: portion of right subclavian A
left: descending aorta

Question 25

How does the development of the arteries contribute to the position of recurrent laryngeal nerves?

Answer 25

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

Question 26

What is the ductus venosus?

Answer 26

V that allows placental blood to bypass liver and go straight from umbilical vein to inferior vena cava

Question 27

Where does oxygen rich fetal blood typically go once it reaches the R atrium?

Answer 27

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

Question 28

What part of the body gets the most oxygen rich blood?

Answer 28

the brain

Question 29

When should the ductus arteriosus close?

Answer 29

72 hours after birth

Question 30

What causes the foramen ovale to close after birth?

Answer 30

Higher pressure in the L atrium

Question 31

What happens at birth in the lungs?

Answer 31

decrease in pulmonary vascular resistance increase in pulmonary blood flow thinning of walls of pulmonary arteries

Question 32

What happens to the ductus venosus after birth?

Answer 32

spincter constricts --> turns into ligamentum venosum

Question 33

What causes the sphincter of ductus venosus to close after birth?

Answer 33

increased O2 --> decreased prostaglandins --> more bradykinin --> smooth muscle contracts

Question 34

What is coarctation of the aorta? | What are the two types?

Answer 34

constriction of the aorta preductal postductal

Question 35

What happens in postductal coarctation of the aorta?

Answer 35

fetus will develop collateral circulation to the body

Question 36

Clinically, what would you see in a baby w/ coarctation of the aorta? How would you treat it?

Answer 36

higher pulses and BP in upper limbs lower bp and weaker pulse in lower limbs give prostaglandins to help open

Question 37

What causes coarctation of the aorta?

Answer 37

we think: smooth muscle abnormally migrates to aorta --> closes it off OR: abnormal remodeling of vasculature

Question 38

How does a double aortic arch occur? | Where do you find it?

Answer 38

persistence of the distal portion of the right dorsal aorta | forms a vascular ring around the trachea and esophagus

Question 39

What do pts present with if they have a double aortic arch?

Answer 39

trouble breathing, stridor esophageal complaints also (due to aortic ring around these two structures that can compress them)

Question 40

What causes an interrupted aortic arch?

Answer 40

both right and left 4th aortic arches are obliterated --> distal R aorta is retained

Question 41

What do babies present w/ if they have an interrupted aortic arch?

Answer 41

weakness, fatigue, poor feeding rapid breathing and heart rate low O2 levels especially in LE

Question 42

DiGeorge' syndrome is associated with what cardiac abnormality?

Answer 42

interrupted aortic arch

Question 43

What happens in abnormal origin of right subclavian artery?

Answer 43

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

Question 44

How does a right aortic arch occur?

Answer 44

L fourth arch and L dorsal aorta are obliterated and replaced by the corresponding vessels on the right side

Question 45

Clinically, what can affect swallowing in right aortic arch?

Answer 45

if ligamentum arteriosum lies on the L side and passes behind esophagus

Question 46

What does the right horn of the sinus venosus give rise to?

Answer 46

sinus venerum and crista terminalis of R atrium

Question 47

What does the L horn of the sinus venosus give rise to?

Answer 47

coronary sinus

Question 48

When does veinous flow to the heart remodeling occur?

Answer 48

weeks 4-8

Question 49

What happens to the vitelline veins proximal to the heart?

Answer 49

Right: persists Left: degenerates

Question 50

What happens to the the vitelline veins in the liver?

Answer 50

right --> hepatic vein | R and L --> form portal vein from gut

Question 51

What happens to the Rt umbilical vein?

Answer 51

degenerates entirely

Question 52

What happens to the L umbilical vein?

Answer 52

proximal degenerates anastomoses w/ ductus venosus distal persists in embryo for placental return

Question 53

What happens to the anterior cardinal Vs?

Answer 53

right --> internal jugular and superior vena cava | Left --> left brachiocephalic V

Question 54

What happens to the posterior cardinal Vs?

Answer 54

drains from body wall degenerates except for root of azygos and common iliac Vs replaced by subcardinal and supracardinal Vs

Question 55

What happens in Left superior vena cava?

Answer 55

persistence of left anterior cardinal v and obliteration of the common cardinal and proximal part of anterior cardinal vs on the R

Question 56

What happens in double superior vena cava?

Answer 56

L anterior cardinal V persists | L brachiocephalic vein fails to form

Question 57

What does the hepatic segment of the inferior vena cava arise from?

Answer 57

vitelline/hepatic veins and sinuses

Question 58

What does the prerenal inferior vena cava arise from?

Answer 58

Rt SUBcardinal V

Question 59

What does the renal vena cava arise from?

Answer 59

subcardinal-supracardinal anastomosis

Question 60

What does the postrenal vena cava arise from?

Answer 60

Rt SUPRAcardinal V

Question 61

What is the round ligamentum teres/round ligament of the liver?

Answer 61

remnant of the umbilical vein

Question 62

How does a fetus compensate for a preductal coarctation?

Answer 62

can bypass through the ductus arteriosus (but this won't work after birth when this closes)