B. THE PHARYNX, BY E. KLEIN. 525 



The thickenings or folds of the mucous membrane of the 

 pharyngeal arch, as well as the walls of the bursa above de- 

 scribed, consist of a loose vascular tissue infiltrated with lymph 

 corpuscles, exhibiting in parts the same structure as that which 

 we have seen in numerous portions of the soft palate. At those 

 points where the poppy-seed-like bodies are observed, the mu- 

 cous membrane presents, over a larger or smaller surface, an 

 adenoid structure closely packed with lymph corpuscles. These 

 infiltrated spots, although constructed on the same plan as the 

 lymph follicles, have, like the similar spots at the root of the 

 tongue, where they are more sparing in number and smaller, 

 no distinct investing membrane. 



Luschka* has denominated this part, first described by La- 

 cauchie,f the Tonsilla Pharyngea, and he agrees with Kolliker 

 in regarding it as an aggregate of lymphatic glands. Henle,J 

 on the other hand, holds it to be conglobate gland substance. 

 It forms a mass of about eight millimeters in thickness, which 

 extends to between the orifices of the Eustachian tubes, from 

 the posterior extremity of the roof of the nasal cavity, with an 

 average length of three centimeters^ 



The glandular tissue is in great part divided into laminae 

 with deep intervening fissures, or is arranged in the form of 

 round sacculi, the walls of which, having an average diameter 

 of one millimeter, are lined by ciliated epithelium and a con- 

 tinuation of mucous membrane, communicating with the ex- 

 terior by a very narrow orifice. The tissue of the mucous 

 membrane covering the arch of the pharynx is differentiated 

 from that of the lower part by the circumstance that it exhibits 

 over surfaces of considerable extent the characters of lympha- 

 tic glandular tissue. 



The mucous membrane of the middle third of the pharynx, 

 though more sparingly than in the upper portion, is also in- 

 filtrated with numerous cellular elements, which are either 

 irregularly distributed through its substance or lie collected 

 into dense masses in a vascular stroma. 



* Luschka, Anatomic des Menschen. Tubingen, 1862, Band i., Abschnitt 1. 

 t Traite (FHydrotomie, 1853, Tab. ii., fig. 10. 

 | Henle, Splanchnologie, p. 146. 



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