2 HUMAN EMBRYOLOGY AND MORPHOLOGY. 



processes (Fig. 8). There is a mesial cleft in the upper lip of 

 hares and rabbits, but it occurs between the two maxillary 



mid brain 



cerebral vesicle. 



eye 



nasal field 



lat. nas. proe. 



mes. nas. proa 



maxillary proc. 



mandib. proc. 



hyoid arch 

 cardiac emin. 



Fig. 1. — Showing the formation of the face by the Nasal, Maxillary, and Mandibular 

 processes in an embryo of the 4th week. (After His.) 



cerebrum 



maxillary process 



nasal field 

 lat. nas. proc. 



mes. nas. proc. (proc. glob.) 



mandib. proc. 

 hyoid arch 



Fig. 2.— Showing the parts of the face formed from the Nasal, Maxillary and 

 Mandibular processes, ' 



processes, the labial part of the middle nasal process being 

 undeveloped. Macrostoma is due to a partial failure of the 



