74 



NORMAL HISTOLOGY. 



A longitudinal section of a spinal ganglion (Fig. 100), which may be 

 taken as a type of such collections, shows the entire ovoid mass to be sur- 

 rounded by a fibrous capsule, continuous with the epineurium ensheathing 

 the nerves. Immediately beneath the capsule, the ganglion-cells are dis- 

 posed in a fairly continuous layer of varying thickness, while the more 

 deeply placed cells are broken up into groups by the tracts of nerve-fibres, 

 a small amount of connective tissue prolonged from the endoneurium of the 

 nerve-bundles and accompanying the blood-vessels being also present. The 



Spinal cord . 



Dorsal root (sensory) 



Spinal ganglion 



Ventral root (motor) 



\ 



Common trunk of spinal nerve 



Ventral or anterior primary division 



^ 



FIG. 100. Section of spinal nerve, showing its roots, ganglion, common trunk and primary 



divisions. X 9. 



majority of the ganglion-cells are from 60-80 [i in diameter, but some meas- 

 ure as much as 170 n, and others as little as 25 p. In sections they usually 

 appear round or oval, since only exceptionallv are their processes to be seen. 

 Each nerve-cell is surrounded by a capsule, lined with flat cells. The ner- 

 vous elements may be grouped into large cells, whose axones give rise o 

 medullated nerve-fibres, and small cells, whose axones continue as non- 

 medullated fibres. Depending largely upon the behavior of their axones, 

 Dogiel has described eleven types of nerve-cells of the spinal ganglia. 

 Sympathetic fibres also are present. 



The sympathetic ganglia correspond in their general structure with 

 those situated on the spinal nerves. They are enclosed by a fibrous capsule, 

 from which prolongations of connective tissue pass into the interior of the 

 ganglion for the support of the nervous elements. The individual ganglion 



