SYMPATHETIC NERVOUS SYSTEM IN MAN 197 



majority of the cells which enter the primordium of this ganglion 

 are derived from the semilunar ganglion along the maxillary 

 nerve and its rami. 



The recent work of Ganfini ('17) shows clearly that the major- 

 ity of the cells which enter the primordimii of the sphenopalatine 

 ganglion in mammalian embryos (guinea-pig and pig) advance 

 from the' semilunar ganglion along the maxillary nerve and its 

 rami. His description of the earhest maxillary rami entering the 

 primordium of the sphenopalatine ganghon as bundles of fibers 

 which deviate from the maxillary nerve near its origin from the 

 semilunar ganglion is in full accord with the conditions in human 

 embryos described above and illustrated microphotographically 

 in figure 23. Ganfini does not consider the cells which may enter 

 the sphenopalatine ganglion via the greater superficial petrosal 

 nerve of any considerable importance in its development. 



Stewart ('20) maintains that both in embryos of the pig and 

 the rat the sphenopalatine ganglion arises exclusively from cells 

 which advance from the geniculate ganghon along the greater 

 superficial petrosal nerve. In the hght of the observations on 

 human embryos set forth above as well as the work of Broman 

 ('11) and Streeter ('12) on human embryos and that of Ganfini 

 ('17) on embryos of other mammalian types, the contribution of 

 cells from the semilunar to the primordium of the sphenopalatine 

 ganglion seems to be so clearly demonstrated that it does not 

 seem advisable at this time to discuss the evidence bearing on 

 this point any further. 



Otic ganglion 



The primordium of the otic ganglion arises in human embryos 

 as an accumulation of cells at the growing extremity of the lesser 

 superficial petrosal nerve. In embryos 7 to 8 mm. n length the 

 tympanic branch of the glossopharyngeal nerve may be traced 

 from the petrosal ganglion along the dorsal aspect of the pharynx 

 as a slender ramus with which are associated numerous cells which 

 are identical with those in the petrosal ganglion. Cells appar- 

 ently advance from the petrosal ganglion into this ramus and 

 migrate along its course. In sagittal sections of an embryo 7.85 

 mm. in length (no. 1354) this ramus may be traced from the 

 petrosal ganglion nearly to the level of the geniculate ganglion. 

 There are no marked accumulations of cells along its course, but 



