atrioventricular canal (AV) cushions

a·tri·o·ven·tric·u·lar ca·nal (AV) cush·ions

(ā'trē-ō-ven-trik'yū-lăr kă-nal' ku'shŏnz)
A pair of mounds of embryonic connective tissue covered by endothelium, bulging into the embryonic AV canal; one located dorsally and one ventrally, they grow together and fuse with each other and with the lower edge of the septum primum, dividing the originally single canal into right and left AV orifices. Frequently seen in patients with Down syndrome.
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