Where do endocardial (AV) cushions arise from?

[voicesinmyhead]

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Im a little confused with heart embryology.

Iv septum (membranous) formed from both bulbar ridges and the endocardial cushions. Bulbar ridges are formed by neural crest migration to the wall of the bulbus cordis. Just confused where the AV or endocardial cushion is?

There is no mention in the FA figures.

Just thought this would make me understand it better,

 

[SBR249]

From wikipedia:

The endocardial cushions are thought to arise from a subset of endothelial cells that undergo endothelial to mesenchymal transition, a process whereby these cells break cell-to-cell contacts and migrate into the cardiac jelly (towards to interior of the heart tube). These migrated cells form the "swelling" seen in the heart tube that is termed endocardial cushions

Source: http://en.wikipedia.org/wiki/Endocardial_cushion

 

[voicesinmyhead]

Actually, i had seen that, but couldnt understand where these endothelial cells are - among the parts of the heart tube - TA, BulbusCordis, PV, PA, etc

Guess it doesnt matter much.

thanks

 

[PL198]

Actually, i had seen that, but couldnt understand where these endothelial cells are - among the parts of the heart tube - TA, BulbusCordis, PV, PA, etc

Guess it doesnt matter much.

thanks

come from BC

" Two endocardial thickenings—anterior and posterior—develop in the bulbus cordis and unite to form a short septum; this joins above with the aortic septum and below with the ventricular septum. The septum grows down into the ventricle as an oblique partition, which ultimately blends with the ventricular septum in such a way as to bring the bulbus cordis into communication with the pulmonary artery, and through the latter with the sixth pair of aortic arches; while the left ventricle is brought into continuity with the aorta, which communicates with the remaining aortic arches."

http://en.wikipedia.org/wiki/Truncus_arteriosus_(embryology)

lol it's the TA page but talking about the BC

 

[J ROD]

I had a question on them.

 

[nidusiamnot]

From the neural crest cells, that are messed up in Downs? Isn't that the reason for the septal defects over secundum defects in the regular babies? I mean idk please correct me if I'm wrong.

 

[SBR249]

Not the endocardial cushions. The neural crest cells give rise to the membranous septum and the septum that divides the outflow tracts but it doesn't really contribute to the septa that divides the atria from the ventricles.

 

[Transposony]

This and this might help.

The endocardial cushions do not directly form the valve components but play an essential role in the process by which undermining and delamination of the myocardium forms the valve leaflets and chordal attachments. Complete failure of fusion of the endocardial cushions results in deficiency of the inlet portion of the interventricular septum, a common atrioventricular valve annulus and common AV valve, as well as deficiency of the inferior (primum) portion of the atrial septum. This constellation of features results in a large defect in communication with all 4 chambers of the heart.

 

[nidusiamnot]

If we're getting into that much detail: http://onlinelibrary.wiley.com/doi/10.1002/dvdy.10418/full

 

[aspiringmd1015]

Kaplan clearly states Neural crest cells, but looks like Kaplan took the easy way out, i havent checked the links you guys provided but ill trust those websites over kaplan