THE SYMPATHETIC NERVOUS SYSTEM 



STRUCTURE OF THE SYMPATHETIC GANGLIA 



341 



The nerve-cells of the sympathetic ganglia are almost all multipolar, but there 

 are also a few that are unipolar or bipolar. Each cell is surrounded by a nucleated 

 membranous capsule. Some of the dendrites ramify beneath this capsule and 

 are designated as intracapsular. Others pierce the capsule, run long distances 

 through the ganglia, and are known as extracapsular dendrites. 



Fig. 251. Neurons from the human superior cervical sympathetic ganglion (pyridin-silver 

 method): A, Three nerve cells and the intercellular plexus: a, unicellular glomerulus; b, neuron 

 with extracapsular dendrites. B, Tricellular glomerulus. C, Neuron surrounded by subcapsular 

 dendrites. 



Intracapsular dendrites are numerous in the sympathetic ganglia of man, 

 but rare in those of mammals (Marinesco, 1906; Cajal, 1911; Michailow, 1911; 

 Ranson and Billingsley, 1918). Beneath the capsule these dendrites may form 

 an open network more or less uniformly distributed around the cell (Fig. 251, C), 

 or they may be grouped on one side of the cell, causing a localized bulging in 

 the capsule (Fig. 251, A, a). Such a localized mass of subcapsular dendrites 

 with interlacing branches is known as a glomerulus. Following CajaPs classifi- 

 cation we may distinguish four types of glomeruli according to the number of 



