noun
: a layer of resilient jellylike material lying between the cardiac endothelium and the epimyocardium in the early development of the vertebrate heart
noun
: a layer of resilient jellylike material lying between the cardiac endothelium and the epimyocardium in the early development of the vertebrate heart
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012