Origin of Cushion Tissue in the Developing Chick Heart: Cinematographic Recordings of in Situ Formation

Abstract
Differential interference microscopy and time-lapse cinematography were used to determine unequivocally the origin of cushion tissue cells migrating in situ in the atrioventricular region of the embryonic chick heart. These studies have verified the presumed endocardial origin of cushion tissue mesenchyme.