106 NORMAL HISTOLOGY ANT> ORGANOGRAPHY. 



system, nerve terminations formed in tissues and 

 organs throughout the whole body. 



General Considerations. Nerve cells are so highly 

 specialized that their multiplication after birth is un- 

 known. We never, therefore, find tumors of nerve 

 cells. If a nerve cell is cut, the axis cylinder re- 

 moved from the nerve cell dies while the end that 

 is still attached to the cell regenerates and may 



Fig- 75- Neurogliar cells: a, from spinal cord of embryo cat; b, from 

 brain of adult cat; stained in chrome-silver (Bohm and Davidoff). 



restore the lost part. Surgeons unite the ends of a 

 cut nerve so that the axis cylinder may develop along 

 the old nerve trunk which becomes a path of least 

 resistance. 



In amputations the cut nerve may grow into a 

 tumor, called a neuroma. Such a tumor would con- 

 sist of nerve fibers and the accompanying connective- 

 tissue elements. Injury to nerve cells, such as 



