CVS Embryology

Question 1

Outline the development of the primordial heart tube

Answer 1

3rd-4th week

Lateral plate splanchnic mesoderm forms CV system

Angioblastic chords canalise and coalesce into heart tubes

Question 2

What type of cells collect into islands and where do they move?

Answer 2

Angioblastic cells form islands and move towards the midline

Question 3

Why does the primordial heart form so early?

Answer 3

Embryo needs transportation of nutrients as it gets bigger

Question 4

What is the growth rate of the bulbus cordis and ventricle?

Answer 4

Quicker than the other structures - forms U-shaped tube called the bunboventricular loop

Question 5

When does atrial and ventricular separation occur?

Answer 5

27th to 37th day

Question 6

Separation includes two actively growing masses - what are they?

Answer 6

The septum and endocardial cushion

Question 7

What does the endocardial cushion separate?

Answer 7

Left and right atrioventricular openings

Question 8

Describe the process of atrial separation

Answer 8

Septum primum forms across foramen primum - then septum secundum develops across foramen secundum

Question 9

Where does the septum secundum form with respect to the septum primum?

Answer 9

On its right

Question 10

Describe ventricular septation?

Answer 10

Muscular septum forms
Leaves IV foramen
Membranous septum closes the IV foramen

Question 11

What is the pathophysiological behind SIDS?

Answer 11

Abnormalities of conducting tissue of the heart

Question 12

What three main pathologies arise from incorrect development of the heart?

Answer 12

Dextrocardia

Transposition of the great vessels - causes cyanotic disease associated with ASD and VSD

Teratology of Fallot

Question 13

What is the teratology of Fallot?

Answer 13

Pulmonary stenosis
VSD
Dextroposition of aorta
RVH

Question 14

How is the primordial heart orientated dorsal to the pericardial cavity?

Answer 14

Cranial folding of embryo

Question 15

Describe the formation of the pericardium

Answer 15

Derived from into-embryonic coelom

Parietal and fibrous - somatic mesoderm

Visceral formed from splanchnic mesoderm

Question 16

What are the potential causes of the teratology of Fallot?

Answer 16

Failure of aorticopulmonary septum to take spiral course

Defective migration of neural crest cells

Question 17

Describe the regions of the primordial heart tubes

Answer 17

Truncus arteriosus 
Bulbus cordis 
Ventricle 
Atrium
Sinus venosus

Question 18

Outline the partition of bulbus cordis and truncus arteriosus

Answer 18

Proliferation of mesenchymal cells during 5th week septates the tube - blood flow causes helication and ultimately divides into pulmonary trunk and aort

Question 19

What are the two processes of vascular development?

Answer 19

Vasculogenesis and angiogenesis

Question 20

What is vasculogenesus?

Answer 20

Defined as new formation of a primitive vascular network

Question 21

What is angiogenesis?

Answer 21

Defined as new growth of vessels from pre-existing blood vessels

Question 22

What are the first arteries to appear in the embryo?

Answer 22

The left and right primitive aortae

Question 23

The primitive aortae are split into what two parts?

Answer 23

Ventral and dorsal

Question 24

The left and right primitive aortae fuse to form what?

Answer 24

The aortic sac

Question 25

What form from the aortic sac?

Answer 25

Aortic branches

Question 26

What occurs at the same time as the new formation of aortic branches?

Answer 26

Pharyngeal arches Each with its own nerve and artery these complexes are now called aortic arches

Question 27

How many aortic arches initially form?

Answer 27

6

Question 28

Where do all aortic arches terminate?

Answer 28

The dorsal aorta

Question 29

What is the fate of the first and second aortic arches?

Answer 29

The maxillary arteries

Question 30

What is the fate of the third aortic arch?

Answer 30

Common carotid and first part of the internal carotid arteries

Question 31

What is the fate of the fourth left aortic arch?

Answer 31

Distal aortic arch

Question 32

What is derived from the right fourth aortic arch?

Answer 32

Proximal portion of the right subclavian vein

Question 33

What is derived from the sixth aortic arch?

Answer 33

Left - left pulmonary artery and ductus arteriosus Right - right pulmonary artery

Question 34

What is the fate of the fifth aortic arch?

Answer 34

Totally regresses

Question 35

What is the pathogenesis of most heart defects?

Answer 35

Regression of a tube the should stay or non-regression of a tube which shouldn't stay

Question 36

What four major pathologies are associated with abnormal cardioembryology

Answer 36

1. Aberrant subclavian vein 2. Double aortic arch 3. Patent ductus arteriosus 4. Coarctation of the aorta

Question 37

What are the three fates of the vitelline arteries?

Answer 37

1. Celiac artery - foregut 2. Superior mesenteric artery - midgut 3. Inferior mesenteric artery - hindgut

Question 38

What is the fate of the umbilical arteries?

Answer 38

Proximal portion - persists to form internal iliac and superior vesical branches (to urinary bladder) Distal portion degenerates and is obliterated to form medial umbilical ligaments

Question 39

What is the function of the vitelline veins?

Answer 39

Carry blood from the yolk sac to the sinus venosus

Question 40

What is the function of the umbilical veins?

Answer 40

Originate in chronic villi of placenta - carrying oxygenated blood to the embryos

Question 41

What is the function of the cardinal veins?

Answer 41

Draining the body of the embryo

Question 42

What are the fates of the vitelline veins?

Answer 42

- Portal veins - Hepatocardiac inferior vena cava - Liver sinusoids - Superior mesenteric veins

Question 43

What are the fates of the umbilical veins?

Answer 43

1. Right and left umbilical veins | 2. Ligamentum vensosus

Question 44

What is the fate of the cardinal veins?

Answer 44

Forms vena caval (SVC and IVC) by anastomoses

Question 45

What are some pathologies associated with venous abnormalities?

Answer 45

Double IVC, absence of IVC, left SVC and double SVC

Question 46

Describe the development of the lymphatic system

Answer 46

Develops at the end of the sixth week, forms six major lymph sacs which later are joined by vessels

Question 47

What three structures are important to consider during the foetuses transition from placental circulation to pulmonary circulation?

Answer 47

Ducti (vensosus and arteriosus) - allows blood to bypass the liver and lungs through the oval foramen

Question 48

What is the ductus venosus?

Answer 48

Vessel which transmits blood from the umbilical vein direct to the IVC, allowing them to bypass the liver

Question 49

What physiological changes are associated with birth?

Answer 49

Foramen vale closes to form fossa ovalis Ducti contract and become ligaments