228 



THE ORGANS 



and deeper parts of the mucosa. From these plexuses, branches are 

 given off which lose their medullary sheaths and form a second 

 plexus of non-medullated fibres just beneath the epithelium. From 

 this subepithelial plexus, branches pass in between the epithelial 

 cells to terminate in end brushes or in tactile corpuscles. The 

 nerves belong to the cerebro-spinal system, and are dendrites of 

 sensory ganglion cells. Axones of sympathetic neurones are also 

 present in the oral mucosa, destined mainly for the muscle-tissue of 

 the blood-vessels. 



TECHNIC 



(i) The superficial cells of the oral mucous membrane maybe prepared for 

 examination as in technic i, page 63. 



(2) For the study of the mucous membrane of different parts of the mouth, 

 fix small pieces in formalin-Miiller's fluid (technic 6, p. 7), cut sections perpen- 

 dicular to the surface, stain with haematoxylin-eosin (technic i, p. 20), and mount 

 in balsam. 



(3) Small mucous and serous glands of the mouth may be studied in the 

 preceding sections. 



The Tongue 



The tongue is composed mainly of striated muscle fibres, sup- 

 ported by connective tissue and covered by a mucous membrane. 



Fungiform 

 papillae 



Fig. 133. — Surface View of Tongue showing liliform papilla and three fungiform 



papillae (Spalteholz). 



While the bundles of fibres interlace in all directions, three fairly 

 distinct planes can be differentiated. 



