CVS Embryology Flashcards
Outline the development of the primordial heart tube
3rd-4th week
Lateral plate splanchnic mesoderm forms CV system
Angioblastic chords canalise and coalesce into heart tubes
What type of cells collect into islands and where do they move?
Angioblastic cells form islands and move towards the midline
Why does the primordial heart form so early?
Embryo needs transportation of nutrients as it gets bigger
What is the growth rate of the bulbus cordis and ventricle?
Quicker than the other structures - forms U-shaped tube called the bunboventricular loop
When does atrial and ventricular separation occur?
27th to 37th day
Separation includes two actively growing masses - what are they?
The septum and endocardial cushion
What does the endocardial cushion separate?
Left and right atrioventricular openings
Describe the process of atrial separation
Septum primum forms across foramen primum - then septum secundum develops across foramen secundum
Where does the septum secundum form with respect to the septum primum?
On its right
Describe ventricular septation?
Muscular septum forms
Leaves IV foramen
Membranous septum closes the IV foramen
What is the pathophysiological behind SIDS?
Abnormalities of conducting tissue of the heart
What three main pathologies arise from incorrect development of the heart?
Dextrocardia
Transposition of the great vessels - causes cyanotic disease associated with ASD and VSD
Teratology of Fallot
What is the teratology of Fallot?
Pulmonary stenosis
VSD
Dextroposition of aorta
RVH
How is the primordial heart orientated dorsal to the pericardial cavity?
Cranial folding of embryo
Describe the formation of the pericardium
Derived from into-embryonic coelom
Parietal and fibrous - somatic mesoderm
Visceral formed from splanchnic mesoderm
What are the potential causes of the teratology of Fallot?
Failure of aorticopulmonary septum to take spiral course
Defective migration of neural crest cells
Describe the regions of the primordial heart tubes
Truncus arteriosus Bulbus cordis Ventricle Atrium Sinus venosus
Outline the partition of bulbus cordis and truncus arteriosus
Proliferation of mesenchymal cells during 5th week septates the tube - blood flow causes helication and ultimately divides into pulmonary trunk and aort
What are the two processes of vascular development?
Vasculogenesis and angiogenesis
What is vasculogenesus?
Defined as new formation of a primitive vascular network
What is angiogenesis?
Defined as new growth of vessels from pre-existing blood vessels
What are the first arteries to appear in the embryo?
The left and right primitive aortae
The primitive aortae are split into what two parts?
Ventral and dorsal
The left and right primitive aortae fuse to form what?
The aortic sac
What form from the aortic sac?
Aortic branches
What occurs at the same time as the new formation of aortic branches?
Pharyngeal arches
Each with its own nerve and artery these complexes are now called aortic arches
How many aortic arches initially form?
6
Where do all aortic arches terminate?
The dorsal aorta
What is the fate of the first and second aortic arches?
The maxillary arteries
What is the fate of the third aortic arch?
Common carotid and first part of the internal carotid arteries
What is the fate of the fourth left aortic arch?
Distal aortic arch
What is derived from the right fourth aortic arch?
Proximal portion of the right subclavian vein
What is derived from the sixth aortic arch?
Left - left pulmonary artery and ductus arteriosus
Right - right pulmonary artery
What is the fate of the fifth aortic arch?
Totally regresses
What is the pathogenesis of most heart defects?
Regression of a tube the should stay or non-regression of a tube which shouldn’t stay
What four major pathologies are associated with abnormal cardioembryology
- Aberrant subclavian vein
- Double aortic arch
- Patent ductus arteriosus
- Coarctation of the aorta
What are the three fates of the vitelline arteries?
- Celiac artery - foregut
- Superior mesenteric artery - midgut
- Inferior mesenteric artery - hindgut
What is the fate of the umbilical arteries?
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
What is the function of the vitelline veins?
Carry blood from the yolk sac to the sinus venosus
What is the function of the umbilical veins?
Originate in chronic villi of placenta - carrying oxygenated blood to the embryos
What is the function of the cardinal veins?
Draining the body of the embryo
What are the fates of the vitelline veins?
- Portal veins
- Hepatocardiac inferior vena cava
- Liver sinusoids
- Superior mesenteric veins
What are the fates of the umbilical veins?
- Right and left umbilical veins
2. Ligamentum vensosus
What is the fate of the cardinal veins?
Forms vena caval (SVC and IVC) by anastomoses
What are some pathologies associated with venous abnormalities?
Double IVC, absence of IVC, left SVC and double SVC
Describe the development of the lymphatic system
Develops at the end of the sixth week, forms six major lymph sacs which later are joined by vessels
What three structures are important to consider during the foetuses transition from placental circulation to pulmonary circulation?
Ducti (vensosus and arteriosus) - allows blood to bypass the liver and lungs through the oval foramen
What is the ductus venosus?
Vessel which transmits blood from the umbilical vein direct to the IVC, allowing them to bypass the liver
What physiological changes are associated with birth?
Foramen vale closes to form fossa ovalis
Ducti contract and become ligaments
