CRANIAL SYMPATHETIC GANGLIA IN THE PIG 



81 



ciliary ganglion. At a later stage, as will be shown presently, 

 the ciliary ganglion becomes connected with the ophthalmic 

 nerve by a fibrous ramies. 



In embryos of the pig 20 to 21 mm. in length in which the 

 eye-muscles are already well differentiated, the ciliary ganglion 

 lies in close proximity with ^he optic stalk, but still remains 

 intimately associated with the oculomotor nerve (fig. 7, Cil). 

 Fibers from this nerve now peiletrate the ganglionic mass. The 

 ciliary ganglion, up to this stage of development, is much more 

 intimately associated with the oculomotor than with the oph- 



Fig. 6 Parasagittal section cutting ophthalmic nerve longitudinally, embryo 

 of pig 14 mm. in length. Cil, ciliary ganglion; Ma, maxillary nerve; MC, migrant 

 cells; Oc, oculomotor nerve; Oph, ophthalmic nerve; S, semilunar ganglion. 



Fig. 7 Parasagittal section cutting ophthalmic nerve longitudinally, embryo 

 of pig 21 mm. in length. Abd, abducent nerve; Cil, ciliary ganglion; Oc, ocu- 

 lomotor nerve; Oph, ophthalmic nerve; OS, optic stalk; (S, semilunar ganglion. 



thalmic nerve. While there can be no doubt that some cells 

 which advance peripherally from the semilunar ganglion along 

 the ophthalmic nerve enter the ciliary ganglion, it is probable 

 that the great majority of the cells which become incorporated 

 in this ganglion are cells which advance peripherally along the 

 oculomotor nerve. At a later stage, as illustrated in figure 8, 

 which is taken from a parasagittal section of an embryo of the 

 cat 22 mm. in length, the ciliary ganglion is connected with the 

 ophthalmic nerve by a fibrous ramus. It is improbable, how- 

 ever, that many nervous elements advance peripherally after this 

 connection is established. 



