SYMPATHETIC GANGLIA 255 



divisions of the trigeminal nerve. These cells, Uke the cells which 

 give rise to the ganglia of the other parts of the sympathetic 

 nervous system, have their origin in a cerebro-spinal ganglion, 

 i.e., a ganglion which is derived from the neural crest, and in 

 motor niduli in the walls of the neural tube and advance peripher- 

 ally along sensory and motor nerve-fibers respectively. 



The ciliary ganglion, as indicated above, bears the same genetic 

 relationships to the oculomotor and the ophthalmic nerves and 

 arises in essentially the same manner in embryos of the pig as 

 in embryos of the turtle and the chick. 



The sphenopalatine ganglion arises, in embryos of the pig, 

 primarily from cells which advance peripherally from the Gasse- 

 rian ganglion along the maxillary nerve. It becomes connected 

 with the geniculate ganglion through the great superficial petrosal 

 nerve but probably receives relatively few^ cells from this source. 

 This ganglion does not bear the same genetic relationship to the 

 great superficial petrosal and the maxillary nerves respectively in 

 the pig as does the ganglion described above as the sphenopala- 

 tine ganglion in the turtle and the chick. 



The otic ganglion arises, in embryos of the pig, at the mesial 

 surface of the proximal portion of the mandibular division of the 

 trigeminal nerve primarily from cells which advance peripher*- 

 ally from the Gasserian ganglion and the wall of the rhombenceph- 

 alon respectively along the sensory and motor roots of this nerve. 

 This ganglion receives a slender sympathetic root but probably 

 few or no cells enter it from this source. The genetic relation- 

 ships of the otic ganglion in the pig differ widely from those of 

 the ganglion described above as the otic ganglion in the chick. 



The submaxillary ganglion arises, in embryos of the pig, in the 

 submaxillary region in proximity with the lingual division of the 

 mandibular nerve from cells which advance peripherally along this 

 nerve. This ganglion bears the same genetic relationship to the 

 mandibular nerve in the pig as in the chick. 



