160 



PERIPHERAL NERVE TERMINATIONS: END ORGANS 



FIG. 



173. NERVE ENDINGS IN THE 

 THELIUM OF THE LARYNX. 



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

 endings in the stratified epithelium are rep- 

 resented. (After Retzius.) 



lar character and by the fact that they occur most abundantly in the 



intcrpapillary portions of the epidermis. The deeper surface of the 



tactile cell rests in a cuplike ex- 

 pansion of a terminal nerve 

 fibril which is known as the tac- 

 tile meniscus. 



3. Neuro-epithelium. The 

 cells of some types of neuro- 

 epithelium, e.g., the olfactory 

 cells, are true nerve cells ; others 

 are modified epithelial cells, in 

 relation to which the nerves ter- 

 minate by intercellular end fi- 

 brils. The neuro-epithelium of 

 the eye and the ear will be de- 

 scribed in the chapters devoted to these organs, that of the gustatory 



organ forms typical nerve end organs, the taste buds. 



TASTE BUDS (Gustatory Organ}. These end organs appear to be 



concerned with the special sense of taste. They occur in the stratified 



epithelium of the base of the 



tongue, uvula, soft palate, 



and epiglottis. Disse has also 



found similar structures in 



the nasal mucous membrane. 



They are most abundant on 



the lateral surfaces of the cir- 



cumvallate papillae of the 



tongue and on the walls of 



the sulci in the foliate pa- 

 pillae which are most highly 



developed in the rabbit. They 



are occasionally found on the 



FIG. 174. TACTILE CELLS IN THE EPITHELIUM 

 OF THE GROIN OF A GUINEA-PIG. 



a, tactile cell; c, epithelial cell; m, tactile men- 

 iscus, at the end of a nerve fibril; n, nerve fiber. 

 Chlorid of gold. Highly magnified. (After 

 Ranvier.) 



fungiform papillae of the 

 tongue, where they occur in 

 considerable numbers in fetal 

 life but mostly disappear be- 

 fore birth, and in the lateral walls of the sulci about the circumvallate 

 papillae. 



Taste buds are ovoid, ellipsoidal, or spheroidal masses which occupy 

 almost the entire depth of the epithelial layer. Their broad base rests 



