This is an intermediate representative of stage 17 as the nose and future upper jaw emerge. The facial parts come into existence as a consequence of the proliferation of the underlying mesenchymal growth centers. These undergo a coalescence of ridge-like masses, each mass differentiating into the various structures of its own region. Both the overlying epithelium and the precocious trigeminal and facial nerve strands appear to participate with the mesenchyme in the regulation of the form of the developing facial components. The field marked by the presence of the auricular hillocks is stippled, and the hillocks are indicated in accordance with the parts of the external ear derived from them.