THE TONGUE. 



881 



FIG. 517. Circumvallate papillae of tongue 

 of rabbit, showing position of taste-goblets. 

 (Stohr.) a. Duct of gland, d. Serous gland. <?. 

 Taste-goblets. I. Primary septa, and r, second- 

 ary septa, of papillae, n. Medullated nerve. 

 M. Muscular fibres. 



extremities, and covered with secondary papillae. Their epithelial investment is 

 very thin. 



The papillce minima (conicae or filiformes) cover the anterior two-thirds of the 

 dorsum of the tongue. They are very mi- 

 nute, more or less conical or filiform in shape, 

 and arranged in lines corresponding in di- 

 rection with the two rows of the papillae cir- 

 cumvallatae, excepting at the apex of the 

 organ, where their direction is transverse. 

 They have projecting from their apices nu- 

 merous filiform processes or . secondary pa- 

 pillae, which are of a whitish tint, owing to 

 the thickness and density of the epithelium 

 of which they are composed, and which has 

 here undergone a peculiar modification, the 

 cells having become cornified and elongated 

 into dense, imbricated, brush-like processes. 

 They contain also a number of elastic fibres, 

 which render them firmer and more elastic 

 than the papillae of mucous membrane gen- 

 erally. 



Simple papillce, similar to those of the 

 skin, cover the whole of the mucous mem- 

 brane of the tongue, as well as the larger 

 papillae. They consist of closely-set, microscopic elevations of the corium, con- 

 taining a capillary loop, covered by a layer of epithelium. 



Structure of the Papilla?. The papillae apparently resemble in structure those 

 of the cutis. consisting of a cone-shaped projection of connective tissue, covered 

 with a thick layer of squamous epithelium, and contain one or more capillary 

 loops, amongst which nerves are distributed in great abundance. If the epithe- 

 lium is removed, it will be found that they are not simple elevations like the 

 papillae of the skin, for the surface of each is studded with minute conical pro- 

 cesses of the mucous membrane, which form secondary papillae (Todd and Bow- 

 man). In the papillae circumvallatae the nerves are numerous and of large size; 

 in the papillae fungiformes they are also numerous, and terminate in a plexiform 

 network, from which brush-like branches proceed ; in the papillae filiformes their 



mode of termination is uncertain. Buried in the 

 epidermis of the papillae circumvallatae, and in some 

 of the fungiformes, certain peculiar bodies called 

 taste-goblets have been described. 1 They are flask- 

 like in shape, their broad base resting on the co- 

 rium, and their neck opening by an orifice between 

 the cells of the epithelium. They are formed by 

 two kinds of cells : the external (cortical) are 

 arranged in several layers ; they are long and flat- 

 tened, with tapering ends, and in contact by their 

 edges, the tapering extremities extending from the 

 base to the apex of the organ. Their apical ends 

 bound the orifice (gustatory pore) just mentioned. 

 They thus enclose the central cells (gustatory cells), 

 which are spindle-shaped and have a large spherical nucleus about the middle of 

 the cell. Both extremities of a gustatory cell are filamentous ; the inner process 

 is described (denied by G. Retzius) as continuous with the terminal fibril of a 

 nerve (glosso-pharyngeal), while the outer one projects as an extremely fine hair 

 through the orifice of the taste-goblet. 2 



1 These bodies are also found in considerable numbers at the side of the base of the tongue, just 

 in front of the anterior pillars of the fauces. 



2 See Englemann, in Strieker's Handbook (New Syd. Soc. Trans.), vol. iii. p. 2. 



56 



FIG. 518. Taste-goblets, a. Central 

 cell. 6. Cortical cell. 



