192 



HISTOLOGY 



neuro-fibrils of the nerve cell and fiber to the motor endings are not 

 known other than that they are direct continuations of one or more of 

 the fibrils which become thicker and separated into a varying number 

 of short branches that develop varicosities and an irregular outline. 

 The terminal varicosities of the various branches sometimes attain con- 

 siderable size, as, for instance, the end -organs of some electric nerves 

 (Fig. 168). In such a case the sarcoplasm or neuroplasm probably 



FIG. 168. A nerve fiber (nv.f.) ending on 

 an electroplax of Astroscopus. The end- 

 plate is large and stained black with silver 

 nitrate. 



FIG. 169. A Purkinje cell from the cerebellum 

 of man, showing the contact of two different 

 motor end-organs of nerve cells with its sensory 

 surfaces, cl.fi., ending of a climbing fiber on 

 the branching dendrites; stell.end., ending of a 

 stellate fiber on a surface of the cell body. 

 (After CAJAL; slightly modified.) 



constitutes some considerable part of the structure in addition to the 

 neuro-fibrils. 



The terminal branches or telodendria of the end-organ are plainest 

 and least irregular as well as, usually, most thickly branched in case 

 they are used to communicate with another nerve cell. 



Examples of efferent end-organs in contact with other nerve cells 

 or their processes are most numerous. The simplest type of such an 

 organ is represented by a sensory nerve cell, as, for instance, the auditory 



