Buccopharyngeal membrane

Overview
Over the crescentic masses of the mesoderm the ectoderm and endoderm come into direct contact with each other and constitute a thin membrane, the buccopharyngeal membrane (or oropharyngeal membrane), which forms a septum between the primitive mouth and pharynx. In front of the buccopharyngeal area, where the lateral crescents of mesoderm fuse in the middle line, the pericardium is afterward developed, and this region is therefore designated the pericardial area.