THE TONGUE 



tissue papilla carries upon its surface many small secondary papillae 

 of the corium, which project into the epithelial coat of the circum- 

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

 lateral margins. 



Mucous and serous glands occur in the deeper portion of the 

 corium of the tongue and among its muscle bundles ; they open 

 upon its epithelial surface between the papillae. These glands are 

 most abundant at the base of the organ but are also found along 

 its margins as far forward as the tip, where a pair of small tubulo- 

 acinar mucous glands lie on either side of the median septum 

 and open upon the ventral surface of the tongue ; these are the 

 anterior lingual glands of Nuhn.* The serous glands of von Eb- 

 ner are confined to the region of the circumvallate papillae at 

 the base of the tongue. They pour their secretion into the val- 

 lum which surrounds the base of the papilla or into the crypts 

 of the lingual tonsil. Other lingual glands, also of the small 

 tubulo-acinar type, occur at various portions of the dorsal surface 

 of the tongue. 



The lingual tonsil (Fig. 153, page 157) is a considerable col- 

 lection of lymphoid nodules which is found at the base of the 

 tongue in and about the median line. These nodules are grouped 

 about a large funnel-shaped crypt, the foramen ccecum, which 

 opens at the apex of the V formed by the group of circumvallate 

 papillae and which in the embryo forms the lingual extremity of 

 the so-called duct of the thyroid gland (thyreo-glossal duct). 

 Several smaller crypts are also included in the region of the 

 lingual tonsil. 



The lymphoid nodules are embedded in the mucosa or corium 

 of the tongue and are surrounded by mucous glands many of whose 

 ducts penetrate between the nodules to open into the branching 

 crypts. Lymphatic corpuscles, apparently derived from the nod- 

 ules, infiltrate the surrounding connective tissue and epithelium 

 and find their way into the lumen of the follicular crypts. 



In other portions of the lingual mucous membrane diffuse col- 

 lections of lymphatic corpuscles are of frequent occurrence, and 

 small nodules occur in many parts of the dorsal mucous membrane 

 toward the base of the tongue. 



The blood vessels of the tongue are supplied by large arteries 

 which, with the corresponding veins, are embedded in the muscular 

 portion of the organ and supply capillary vessels to this tissue. 



* Mannheim, 1845. 



