Cardiovascular Embryology

Question 1

What is vasculogenesis?

Answer 1

De novo development of blood vessels from endothelial cell differentiation in situ - genetically programmed to form

Restricted to development

Question 2

What is angiogenesis?

Answer 2

Formation of blood vessels from sprouting of new capillaries from existing vessels

Occurs across the whole lifespan

Question 3

Where does vasculogenesis originate from?

Answer 3

Yolk sac and trophoblast layer.

• mesoderm ‘blood islands’ which contain haemangioblasts in extra embryonic tissues

Question 4

What are the layers of the tertiary villi?

Answer 4

Initially,

1. Syncytium
2. Cytotrophoblast
3. Connective tissue
4. Endothelium

Then

1. Syncytium
2. Endothelial

Diffusion distance decreases = more diffusion

Question 5

4 unusual features of placenta?

Answer 5

• forms from embryo and mother
• maternal blood is exposed to non-maternal tissue and there is no immune response - syncitiotrophoblasts modulate immune system
• lots of simultaneous tasks
• limited life span

Question 6

How do vessels formed in vasculogenesis form a primary vessel?

Answer 6

Blood islands fuse and endothelial cells are arranged into vessels —> join together and form a main vessel

Question 7

Describe early heart formation

Answer 7

• clusters of endocardial cells (angioblasts)and cardiac myoblasts from mesoderm
• form heart tube and dorsal aortae (vasculogenesis)
• heart tube and pericardial cavity pushed towards thoracic region

Question 8

What does heart tube form?

Answer 8

• Truncus arteriosus
• bulbus cordis
• primitive ventricle
• primitive atrium
• sinus venosus

Question 9

What is cardiac dextral looping?

Answer 9

Corrects venous blood flow from entering the left ventricle so that it enters the right ventricle

Question 10

Describe foetal circulation

Answer 10

Umbilical vein —> ductus venosus (+ sinus hepatis) —> IVC —> right atrium —> right ventricle and left atrium (via foramen ovale) —>aorta (right ventricle —> pulmonary artery —> aorta via ductus arteriosus) —> rest of body

Blood bypasses lungs

Question 11

Changes at birth

Answer 11

• umbilical vein —> ligamentum teres
• ductus venosus —> ligamentum venosum
• ductus arteriosus —> ligamentum arteriosum
• Foramen ovale —> fossa ovalis

Question 12

List 4 congenital heart defects

Answer 12

• Ventricular septal defects
• Patent ductus arteriosus
• Transposition of great vessels
• Tetralogy of fallot

Question 13

What are the 4 features of tetralogy of fallot?

Answer 13

• Overriding aorta
• Pulmonic stenosis
• Ventricular septal defect
• Right ventricular hypertrophy