748 



SPECIAL SOMATIC AND VISCERAL RECEPTORS 



The Structure of the Taste Buds. These peculiar bodies are 

 widely distributed through the mucous membrane lining the mouth 

 and pharynx. 1 They are found upon the tip, margins and posterior 

 region of the dorsal aspect of the tongue, but not upon its lower sur- 

 face. Limited numbers of them may also be detected in the mucosa 

 of the fauces and adjoining regions of the pharynx and epiglottis. 

 In children they are more numerous than in adults, invading even the 

 adjoining regions of the cheeks and posterior fauces. These outlying 

 taste buds atrophy in later years. This retrogression also involves 

 those occupying the median area of the tongue. 



The taste buds appear as oval bodies, measuring 80ju in length 

 and 40/x in width. Externally they are enveloped by the cortical 

 reticular cells, while their central portion is occupied by a number of 



FIG. 372. FIG. 373. 



FIG. 372. DIAGRAMMATIC REPRESENTATION OF CIRCUMVALLATE PAPILLA SHOWING THE 

 POSITION OF THE TASTE-BUDS. 



FIG. 373. TRANSVERSE SECTION THROUGH A TASTE-BUD. 



A, taste pore; B, spindle-shaped cells of the taste-bud; C, reticular cells; D, nerve 

 fibers terminating among its cells. 



closely packed, elongated cells which send their hair-like projections 

 into the depression overlying them. This depression, which is known 

 as the taste-pore, is the seat of the stimulation leading to taste sensa- 

 tions. The nerve fiber enters through the basal pole of the taste-bud 

 and terminates in arborizations among the different gustatory cells. 

 These fibers lose their medullary sheath directly before entering. 



It has just been stated that these end-organs communicate with 

 the general cavity of the mouth through the taste-pore. Many of 

 them, however, do not lie directly upon the surface, but occupy a posi- 

 tion in the depressions between the different elevations of the mucosa. 

 The tongue, for example, exhibits three types of elevations which, in 

 accordance with their shape, are known as filiform, fungiform and 

 circumvallate papillae. Those mentioned last are found chiefly upon the 

 posterior aspect of this organ and are beset with an especially large 



1 First described by Loven and Schwalbe in 1867. 



