TISSUES. 



97 



2. Bipolar Nerve Cells. Bipolar nerve cells have 

 two processes, one axis cylinder and one dendrite. 

 Nerve cells of the spinal ganglia and ganglia of the 



Nerve fibers in cross section. 



Nucleus of nerve 

 cell. 



Nucleolus. 



Connective-tissue cells forming a capsule 

 around the nerve cell. 



Fig. 63. Two bipolar nerve cells from the spinal ganglion. 



cranial nerves belong to this class. These cells 

 apparently are unipolar, but their embryology 

 clearly shows the single process to be morphologically 

 equivalent to two. In 

 this particular case 

 the long peripheral 

 process carries an im- 

 pulse to the cell, and 

 this long process is 

 therefore a dendrite. 

 The short process that 

 unites the ganglion 

 with the central ner- 

 vous system is the 

 axis cylinder. These 

 large bipolar cells are 



Fig. 64. Three ganglion cells from 

 a spinal ganglion of a rabbit embryo. 

 The cells are still bipolar. Their proc- 

 esses come together in later stages, 

 and finally form the T-shaped structure 

 seen in the adult animal; chrome-silver 

 method (Bohm and Davidoff). 



surrounded by a cap- 

 sule of connective-tissue cells. The cells are large and 

 the single compound process very soon divides into 

 the two processes mentioned above. The cytoplasm 



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