Cardiovacular Embryology- Melissa (3)* Flashcards
(41 cards)
By what weeks (gestation) have the endocardial tubes formed?
2-3 weeks (18-19 days)
By what week gestation do the paired endocardial tubes fuse and establish trunks arteriosis outflow?
3 weeks
By when do contractions begin in the fetal heart?
3-4 weeks; 22-23 days
What is happening during week 4 gestation in terms of heart development?
heart tube continues to elongate, curves to form S shape
also circulation begins d27-29
When does atrial and ventricular separation start?
When is it complete?
Week 5/ Day 26
Complete (4 chambers closed) by day 50
At what point does the foramen ovale close?
What rudimentary structure is left?
Week 37/ 38 (after birth in response to the pressure difference)
*Fossa Ovalis remains
Describe the 3 steps that lead up to formation of the single heart tube:
- medial migration of angiogenic cells
- formation of 2 endocardial tubes
- fusion of endocardial tubes (cranial–>caudal) during lateral folding of the embryo
List the 5 dilations of the single heart tube (Cranial–> caudal):
- Truncus arteriosis
- Bulbus cordis
- Primative ventricle
- Primative atrium
- Sinus Venous
Truncus arteriosis derivatives (2):
- proximal aorta
2. proximal pulm. arteries
Bulbs Cordis derivatives (2):
- smooth part of R ventricle (conus arteriosis)
2. Part of left ventricle (smooth also, bc its membranous septum?)
Primitive ventricle derivatives:
Trebeculated portion of rt and lt ventricles
Primitive atrium derivatives:
R (trabeculated), L atria
Sinus venosus derivatives:
- smooth R atrium (R horn)
- coronary sinus (L horn)
- oblique vein
Describe the process of DEXTRAL folding:
What is happening?
Why?
What is the end result?
- Bulboventricular sac grows faster than rest of embryo/ pericardial sac
- Tube folds to the RIGHT–> forms
bulbovenvricualr fold–> organ shifts LEFT - Atrium + sinus venous move dorsal/ cranial and enter pericardial sac
What is the first organ to treat rt/lt symmetry?
Heart!
By when is folding of the heart and migration of neural crest cells to the outflow tract complete?
Day 28 (week 4)
Describe the order of events in atrial septation (6):
- SEPTUM PRIMUM forms
(roof of atrial segment–> endocardial cushion) - SP forms boundaries of FORAMEN PRIMUM
- Apoptosis in posterior SP–> FORAMEN SECUNDUM
- SP closes
- SEPTUM SECUNDUM froms to Rt of SP
(roof of atrial segment–> endocardial cushion) - SS grows in arc anteriorly–> FORAMEN OVALE
What is the foramen ovale/ when is it TECHNICALLY formed?
Foramen ovale is ostium secundum covered by septum secundum. Foramen ovale cannot be called foramen ovale until: septum secundum forms + septum primum joins endocardial cushions.
(Very clear and concise; was trying to describe how s.secundum doesn’t totally close–thank you Leah, for revising :)!)
Describe atrioventricular canal formation (2):
- fusion of superior + inferior endocardial cushions–>
Rt, Lt atrioventricular orifices form - mesenchymal cells form fibrous part of M/T (AV) valves
Describe separation of truncus arteriosis (3):
- neural crest cells elongate outflow tract + aortic arch
- ingrowth of 2 opposing mesenchymal ridges
- spiraling configuration and fusion of ridges (distal–> proximal)
Which three structures fuse to make the membranous portion of the intraventricular septum?
From what heart dilations do they derive?
- Rt bulbar ridge (bulbs cordis)
2, Lt bulbar ridge (bulbs cordis) - AV septum (endocardial cushions)
By what process do the AV valves form?
Delamination of leaflets from superficial myocardium
*Note: myocardium is MESENCHYMAL tissue.
(+ Selective apoptosis to form gaps between leaflets)
How does the muscular portion the ventricular septum form?
How do the 4 chambers all close off?
- apical portions of ventricles balloon out;
- merger of the muscular ventricular septum with the outflow separation closes off the 4 chambers
Derivatives of first aortic arch
Maxillary and external carotid artery (ECA)
