relationship loss: develops_from endocardial ring (TAO:0005072)[TAO]

GO graph seems to suggest this is an endothelium. WP: The endocardial cushions are thought to arise from a subset of endothelial cells that undergo epithelial to mesenchymal transformation, a process whereby these cells break cell-to-cell contacts and migrate into the cardiac jelly (towards to interior of the heart tube). Latest (2010-06-01) new def suggested for GO, added above. Note that EHDAA2 has a more detailed model which we may later adopt. JB: Patterning makes the cushions lay down connective tissue in three domains that force out the local endothelial lining and so the leaflets form

http://upload.wikimedia.org/wikipedia/commons/c/c7/Gray465.png

Swellings of tissue present between the endocardial and myocardial cell layers that will give rise to the interstitial cells of the cardiac valves.[TAO]

uberon

atrioventricular canal cushion, endocardial cushions

(Cardiac valve formation in vertebrates) In response to a myocardial signal, endocardial cells at chamber boundaries take on a mesenchymal character, delaminate and migrate into the cardiac jelly. There, they form an endocardial cushion that is later remodelled into a valve.[well established][VHOG]

UBERON:0002062

• atrioventricular septum
• ventricular septum intermedium
• cardial valve