CHAPTER IX 



PERIPHERAL NERVE TERMINATIONS: 

 END ORGANS 



ALL peripheral nerve fibres end either as terminal fibrils or in 

 relation to a highly specialized end organ. The function of these 

 latter bodies is apparently included in the changing of ordinary 

 stimuli mechanical, thermal, chemical, etc. into a nerve im- 

 pulse, or, vice versa, the changing of a nerve impulse to a cell 

 stimulus which results in motion, secretion, etc., according to the 

 nature of the tissue cells which are thus stimulated. Some of the 

 nerve end organs are connected with centrifugal (motor) fibres, 

 others with centripetal (sensory) fibres. Nerve endings are found 

 in nearly all the tissues of the body with the exception of carti- 

 lage and the calcareous tissue of the bones. 



NERVE ENDINGS IN EPITHELIUM 



Intra-epithelial nerve fibrils are derived from nerve fibre plex- 

 uses in the subjacent connective tissue ; the epithelium usually 

 receives a very abundant 

 nerve supply. The follow- 

 ing types of intra-epithelial 

 nerve endings have to be 

 considered. 



I. END FIBRILS. This 

 form of nerve termination 

 has been demonstrated in 

 all the varieties of epithe- 

 lium. Terminal nerve fibres 

 enter the epithelial tissue 

 as naked fibrils, often some- 

 what varicose, which form a 



delicate plexus between the epithelial cells. The terminal fibrils 

 of this plexus frequently end in minute knob-like enlargements 



123 



FIG. 118. NERVE ENDINGS IN THE EPITHELIUM 

 OF THE LARYNX. 



On the left a taste bud ; on the right, nerve 

 endings in the stratified epithelium are repre- 

 sented. (After Ketzius.) 



