386 



NORMAL HISTOLOGY. 



reach and impress the gustatory cells within the taste-buds. Pore-canals are 

 not, however, invariably present, since, as pointed out by Graberg, certain 

 taste-buds remain immature and retain their embryonal form and relations, 

 being broad and conical and in contact with the free surface. In such buds 

 the gustatory cells are few, only two or three, and so superficially placed that 

 a distinct canal is absent. Occasionally double buds are encountered in 

 which two gustatory bodies are implanted by a common base, but partly 

 retain their independence in having separate distal poles, each provided with 

 its separate taste-pore and canal. 



The chief position of the taste-buds is within the epithelium lining the 

 sides of the annular groove on the circumvallate papillae, the buds being 

 more numerous and closely placed on the median than on the lateral wall of 

 the furrow. Their number has been variously estimated, but it is probable 

 that from 100 to 150 represents the maximum for a single papilla. The local- 



Epithelium 



Central part of 



papilla 



connective tissue 



Taste-bud 



Annular wall 



Gland-duct 



Serous gland 



Muscle fibres 



FIG. 435. Section across circumvallate papilla from tongue of child ; the taste-buds are seen within the 



epithelium. X 45. 



ity of next importance numerically is the papillae foliatae on the sides of the 

 tongue in the furrows of which, even in man, the taste-buds are plentiful. 

 Additional situations, in which, however, the taste-buds are very sparingly 

 and uncertainly distributed, include the fungiform papillae, the soft palate, 

 the posterior surface of the epiglottis and the mesial surface of the arytenoid 

 cartilages. Within the fungiform papillae a few buds may be found on the 

 free surface, where the epithelium is thinnest. Over the soft palate their dis- 

 tribution is irregular and uncertain, while in the larynx the buds are limited 

 to the areas covered by squamous epithelium. 



Wherever found, the taste-buds consist exclusively of epithelial tissue 

 and, in correspondence with other sense-organs, include two chief varieties 

 of elements the supporting cells and the more highly specialized neuro- 

 epithelium, the gustatory cells, among which lie the terminal fibrillae of the 

 nerve of taste. 



The supporting cells are represented principally by elongated epithe- 

 lial elements that occupy both the superficial and deeper parts of the taste- 

 buds of which they contribute the chief bulk. They vary in their individual 

 contour, being lanceolate, wedge-shaped or columnar, according to the 

 modelling to which they are subjected by the neighboring cells. They pos- 

 sess large clear vesicular nuclei that contain little chromatin and, therefore, 

 stain faintly. The position of the nucleus is inconstant, in some cells being 

 near the base and in others in the middle or nearer the apex. The periph- 



