One differentiates between a dorsal, a ventral and two smaller lateral -so, in total, four - endocardial cushions. The cellular proliferation on the 23rd and 30th day of development, they narrow the primitive artrioventricular in the form of an H. At the end of development, there is a complete separation between a left and right artrioventricular channel. This process forms important ontogenetic points of cardial development, together with the subsequent septation of ventricle, atrium and cardial bulb.
