HISTOLOGY 



branches. They are said to occur normally only in adults, and especially 

 in old age, being very numerous in the nodose ganglion of the vagus 

 nerve. 



Another feature which, in man, has been found almost exclusively 

 in the nodose ganglion of adults, is the occurrence of "fenestrated cells." 

 These are ganglion cells with peripheral vacuoles, which may break down 

 so that the cell appears multipolar (Fig. 135, 7). Sometimes they are so 

 arranged that the cell process seems to grow out by several roots (Fig. 

 135, 8). Although the fenestrated cells increase in number with advancing 

 age, they are not considered pathological, since they occur in young dogs 

 and other animals. 



Less conspicuous than the large cells with medullated fibers, but more 

 numerous, are small pyriform cells with non-medullated fibers (Fig. 135, 

 4). Ranson, from his own and previous observations, concludes that in 

 the cat and rat, in which the cells have been carefully counted, about 



Sheath. Sheath. 



A B 



FIG. 136. CELLS OF THE HUMAN SYMPATHETIC GANGLIA. (Prepared by L. R. Muller.) X 463. 

 A, From the ciliary ganglion; B, from the superior cervical ganglion. 



two-thirds of the spinal ganglion cells may be classified as small, and are 

 associated with non-medullated fibers (Amer. Journ. of Anat., 1911, vol. 

 12, pp. 67-87). 



The spinal ganglion cells are sometimes surrounded by fine networks 

 of non-medullated fibers, which are probably the terminal branches of 

 medullated fibers derived from cells in the sympathetic ganglia (Fig. 135, 

 i). Branches of the sympathetic fibers are also distributed to the blood 

 vessels in the ganglion. Whether any fibers pass through the spinal 

 ganglion without connecting with its nerve cells is still uncertain; they have 

 not been demonstrated in mammals. 



Sympathetic Ganglia. The sympathetic ganglia consist of multipolar 

 cells which are smaller than those of spinal ganglia (Fig. 136). Their 

 round or oval nuclei, often eccentric, have prominent nucleoli and a loose 

 chromatin network, as in other nerve cells; some of them contain two 



