GANGLIA. 303 



A similar structure as that described is found in the ganglion 

 (ausseri, ganglion jugulare, plexus nodosus n. vagi, ganglion 

 petrosum n. glosso-pharyngei, and the ganglion geniculi n. 

 facialis. 



The ganglion spirale cochleae and ganglion vestibulare are 

 distinguished from the spinal ganglia by the fact that the 

 cells are bipolar. 



The sympathetic yanylia contain multipolar ganglion cells 

 which are smaller than those of the spinal ganglia (13-40 ^ in 

 diameter). They contain pigment granules and often two 

 nuclei, and are surrounded, like the spinal ganglion cells, by 

 a nucleated capsule. These cells give off an axone which 

 possesses no medullary sheath and becomes a fibre of Remak ; 

 or may, on the other hand, become medullated and run periph- 

 eralward. All these fibres originating in sympathetic cells 

 are to be regarded as cellulifugal. They end either in the 

 smooth muscle of the intestinal walls, the vessels, the arrec- 

 tores filorum, the iris, the corpus ciliare, etc., or in the mucous 

 membranes, and the glands (liver, kidney, etc.), where they 

 influence the secretory function. 



The dendrites, of which the sympathetic cells possess many, 

 are short. They branch many times and form at their ends 

 fine networks which surround other cells. Besides the cells, 

 we find in the sympathetic ganglia nerve fibres partly medul- 

 lated and partly non-medullated. The latter arise from the 

 cells of the ganglion itself, while the former are medullated 

 cerebro-spinal fibres which have passed over to the sympathetic 

 system through the rami communicantes. These are partly 

 sensory and partly motor fibres. The sensory ones run to the 

 periphery and end there; the motor end, on the contrary, 

 in the sympathetic ganglion, where they form pericellular 

 networks around the ganglion cells. In this way the sym- 

 pathetic cells are influenced by the motor fibres of the cerebro- 

 spinal system. The sympathetic nerve cells themselves, how- 

 ever, send their axones to the periphery, where they end freely, 

 so that the cerebro-spinal fibres may be considered as motor 



