Heart embryology and morphogenesis

Question 1

What does the truncus arteriosus give rise to?

Answer 1

Ascending aorta and pulmonary trunk

Question 2

What does the bulbus cordis give rise to?

Answer 2

Smooth parts (outflow tract) of left and right 
ventricles

Question 3

What does the primitive atrium give rise to?

Answer 3

Trabeculated part of left and right atria

Question 4

What does the primitive ventricle give rise to?

Answer 4

Trabeculated part of left and right ventricles

Question 5

What does the primitive pulmonary vein give rise to?

Answer 5

Smooth part of left atrium

Question 6

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

Answer 6

Coronary sinus.

Question 7

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

Answer 7

Smooth part of right atrium (sinus venarum)

Question 8

What does the right common cardinal vein and right anterior cardinal vein give rise to?

Answer 8

Super vena cava.

Question 9

Big picture: what are the steps of cardiac morphogenesis?

Answer 9

1. Myocardial specification
2. Formation of linear heart tube
3. Cardiac looping
4. Septation of the chambers
5. Outflow tract formation
6. Valve development

Question 10

How early are cells assigned myocardial fate?

Answer 10

As early as first few weeks - heart beats spontaneously by week 4.

Question 11

What is the cardiac crescent?

Answer 11

Group of cells on the anterior rim that will form the heart tubes.

Question 12

From what does the linear heart tube initially form?

Answer 12

Two separate tubes that migrate to the midline and fuse

Question 13

Why is dorsal mesocardium important?

Answer 13

It suspends the developing heart from the rest of the embryo; very important bc all the vessels going in/out of heart must travel in the dorsal mesocardium

Question 14

Where does the heart beat in the linear heart tube come from?

Answer 14

Intrinsic pacemaker activity of heart tube cells, caudal > cranial

Question 15

In what direction is blood flow in the linear heart tube?

Answer 15

Caudal to cranial

Question 16

When does cardiac looping begin?

Answer 16

Week 4 of development

Question 17

What does cardiac looping establish?

Answer 17

Left to right polarity

Question 18

What can cause dextrocardia?

Answer 18

Defect in L/R dynein, as seen in Kartagener syndrome (primary ciliary dyskinesia)

Question 19

Where is the atrioventricular canal and what does it give rise to?

Answer 19

In between atrium and Left ventricle section on looped primary heart tube; gives rise to the mitral and tricuspid valves

Question 20

What forms the valve of the foramen ovale?

Answer 20

Septum secondum and leftover septum primum

Question 21

How is a patent foramen ovale caused?

Answer 21

By failure of septum secondum and septum primum to fuse after birth.

Question 22

What can a patent foramen ovale cause?

Answer 22

Allows venous thromboemboli to enter systemic circulation instead of getting caught in the lungs; can result in stroke or arterial thromboembolism.

Question 23

What are the three components of closure of the interventricular foramen?

Answer 23

1) proliferation of muscular tissue

2) Aorticopulmonary extension and 3) endocardial cushion extension form membranous portion of interventricular septum

Question 24

Where are ventricular septal defects commonly found?

Answer 24

In the membranous portion of the septum.

Question 25

What stimulates outflow tract formation?

Answer 25

Migration of neural crest cells to drive spiral aorticopulmonary septum growth and fusion

Question 26

Without proper neural crest migration and outflow tract formation, what kind of defects may been seen?

Answer 26

Tetralogy of Fallot, TGA, persistent truncus arteriosus, cardiac abnormalities of 22q.

Question 27

From what structure are mitral/tricuspid valves derived?

Answer 27

AV canal endocardial cushions

Question 28

From what structure are aortic/pulmonary valves derived?

Answer 28

Outflow tract endocardial cushions.