NOSE 



158 



produced by the walls of the groove being caught between the growing lateral nasal 

 and maxillary processes (Lewis). 



The mesial nasal process now becomes united with the lateral nasal and maxillary 

 processes by the extension of mesenchyme between them, and the epithelial raphe 



septal carfil ><</' 





lateral 

 cartilage 



, W .. lateral 



''' OJ-'Vs cartilage 



plug 



plug 



FIG. 196. HORIZONTAL SECTION OP THE NASAL FOSSAE OP A HUMAN EMBRYO OF 30 MM 



(T. H. Bryce.) 



J.o., Jacobson's organ ; con., conchoe ; nd, lacrymal ducts ; nd l , their openings into the nasal 

 fossee ; oss., commencing ossification in maxilla. 



is inteiTupted. It persists behind, however, and forms a thin membrane (bucco- 

 nasal membrane), which breaks through later, so that a passage is established 

 between the hitherto blind nasal sac and the stomodceum (fig. 195). The two 

 openings thus produced are the primitive posterior nares (choance). The united 



