THE DIGESTIVE TRACT. 



155 



occupying almost the entire thickness of the epithelium. Additional 

 taste-buds are found in the folds in the vicinity of the circumvallate 

 papillae, as likewise on some fungiform papillae. At the sides of the 



r2 



Section of circumvallate papilla from tongue of child: a, main central elevation, surrounded by the 

 annular ridge (6) and the intervening deep furrow ; c, taste-buds within the epithelium ; d, ducts of 

 neighboring glands (g, g") ; e, blood-vessels. 



tongue, just in front of the anterior pillars of the fauces, are groups 

 of parallel folds containing a number of taste-buds ; these folds con- 

 stitute the papillae foliatae, which are highly 

 developed in some of the lower animals, as in 

 the rabbit. 



The taste-buds are oval, flask-shaped 

 bodies, embedded within the epithelium, occu- 

 pying usually the entire thickness of the latter, 

 with their long axes placed in general vertically 

 to the free surface of the epithelium. Each 

 taste-bud consists of an enveloping layer of 

 greatly-elongated epithelial cells, the cortical 

 or tegmental cells, which form a complete 

 covering, except over a small area correspond- 

 ing to the superficial pole of the bud ; at this 

 point a minute canal, the taste-pore, connects 

 the interior of the bud with the surface of the 

 mucous membrane. 



Within the epithelial capsule lies a group of 

 highly-specialized elements, the gustatory 

 cells. These neuro-epithelial elements appear 

 as spindle, rod-hTceTor forked cells, each being 

 possessed of an oval nucleus situated about the centre of the elon- 

 gated body. The peripheral or outer ends of these cells are usually 

 prolonged with fine pointed extremities, some of which terminate in 

 stiff hair-like processes projecting within the taste-pore almost as 



Taste-bud from circumval- 

 late papilla of child. The 

 oval structure is limited to 

 the epithelium (e) lining the 

 furrow, encroaching slightly 

 upon the adjacent connec- 

 tive tissue (/") ; o, taste-pore 

 through which the taste-cells 

 communicate with the mucous 

 surface. 



