THE TONGUE 



341 



variety, though much less abundant than the former, is still very 

 numerous and may be found upon any or all portions of the dorsum 

 of the tongue, where they are irregularly scattered among the filiform 

 papillae. The fungiform variety are most abundant near the margin 

 of the tongue on its dorsal surface. Their maximum height is about 

 1.5 millimeters. 



Tli e . CircumvaUate . Papillae. The circumvallate papilla? form a 

 group of from eight to twelve 

 elevations which are situated 

 at the base of the tongue, and 

 are arranged in the form of a 

 V, the apex being directed 

 toward the larynx. These 

 papilla? are much broader (2 

 to 3 millimeters) than either 

 of the former varieties. They 

 extend slightly above the gen- 

 eral level of the epithelial sur- 

 face, are of an inverted coni- 

 cal shape, and are covered by 

 a smooth layer of stratified 

 'squamous epithelium. Their 

 base is surrounded by a deep 

 circular excavation, lined by 

 an invagination of the layer 

 of stratified epithelium, 

 which thus forms a deep 

 trench about the base of the 

 papilla. 



The epithelium which 

 covers the sides of the cir- 

 cumvallate papillae, as well as that forming the lateral wall of the trench 

 contains large numbers of TASTE BUDS (see Chap. VI). The large cen- 

 tral connective tissue papilla carries upon its surface many small sec- 

 ondary papillae of the corium, which project into the epithelial coat of the 

 circumvallate papilla upon its free surface, but are not found upon its 

 lateral margins. 



On the lateral margins of the tongue, just in front of the anterior 

 pillars of the fauces, occur a variable number of transverse parallel 

 folds or leaves, the foliate papillae. These are only slightly developed 



FIG. 321. A FILIFORM AND A FUNGIFORM 

 PAPILLA, FROM AN INJECTED SPECIMEN OF 

 TONGUE OF CAT. 



