THE PALATINE TONSIL 



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enlarged following tonsillar infection, that it has been called the tonsillar lymph gland (Wood). 

 There are also communications with the submaxillary and superficial cervical lymphatic nodes. 

 The tonsillar lymphatic vessels connect also with those of the lingual tonsil in the root of the 

 tongue. 



The tonsillar ring. — The two palatine tonsils, together with the lingual tonsil below and the 

 pharj'ngeal tonsil above, form an almost complete ring of characteristic tonsillar tissue sur- 

 rounding the pharynx and known as Waldeyer's 'tonsillar ring' (fig. 890). It is a highly 

 specialized development of the diffuse lymphoid tissue which is found everywhere in the mucosa 

 of the alimentary and respiratory tracts. It may be noted that the 'tonsillar ring' corre- 

 sponds to the anterior limit of the embryonic foregut, hence the epithelium is of endodermic 

 origin. The arrangement of the tonsils, together with their lymphatic connections, has sug- 

 gested the widely accepted view that they are to be considered as protective mechanisms 

 whose function is to intercept infectious material which has entered the mouth or nasal cavities. 

 This theory is supported by the experiments of v. Lenart, who found that substances injected 

 into the nasal mucosa are intercepted partly in the tonsils, and partly in the cervical lymph 



Fig. 891.— The Left Palatine Tonsil, Showing the Arterial Supply. 

 1, Mesial aspect. 2, Postero-lateral aspect. E, lateral surface. B, posterior surface. 

 T, medial surface. G, groove for pharyngo-palatine muscle. C, capsule. PT, plica triangu- 

 laris. Arteries: AA, anterior tonsillar (from dorsal lingual); PA, posterior tonsillar (from 

 ascending pharj^ngeal) ; SA, superior tonsillar (from descending palatine); lA, inferior tonsil- 

 lar (anterior from dorsal lingual; posterior from tonsillar branch of internal maxillary). (Fet- 

 terolf: Amer. J. Med. Sc, 1912.) 



nodes. Oppel, however, opposes this view, holding that the function of the tonsils, as of lym- 

 phoid tissue elsewhere, is merely the production of lymphocytes. 



Development of the tonsil. — According to Hammar, the palatine fossa (sinus tonsillaris) 

 is a derivative of the second inner branchial groove and is visible in the human embryo of 17 

 mm. There appears in the floor of the fossa a tubercle (tuberculum tonsillare) which later 

 becomes atrophied, excepting a portion which is converted into the plica triangularis. The 

 primitive tonsil becomes divided into two lobes, upper and lower, by a fold (plica intratonsillaris) 

 which later usually disappears. In the foetus of about 100 mm. (crown-rump length) the 

 epithelium of the floor grows into the subjacent mesenchyme in the form of somewhat irregular 

 solid sprouts of epithelium. These later become hollow and form the crypts. Around them, 

 in about the sixth foetal month, the lymphoid tissue begins to accumulate, at first diffusely, 

 later forming characteristic follicles. The lymphocytes arise in situ from the connective- 

 tissue cells (Hammar) or by immigration from the blood-vessels (Stohr). Retterer's claim 

 that the tonsillar lymphoid cells are derived from the epithelial cells has not been confirmed. 



The later foetal development of the tonsil is subject to considerable individual variation. 

 The supratonsillar fossa is a remnant of the upper part of the primitive sinus tonsillaris, which 

 may be transformed into a canal by growth of adenoid tissue around it. It is inconstant and 

 quite variable in size and extent. A portion of the sinus may likewise persist anteriorly (an- 

 terior tonsillar fossa) between the tonsil and the plica triangularis, but this portion is usually 

 obliterated by fusion of the plica with the tonsil. The occasional retro-tonsillar fold and fossa 

 are said to arise secondarily (Hammar). 



Variations in the tonsil. — -The palatine tonsil, like the lingual and pharyngeal tonsils, is an 

 exceedingly variable organ. Many of the variations are developmental in origin, as above 

 indicated, and are therefore congenital. Furthermore, the tonsils, like all lymphoid structures, 

 are subject to marked age variations. Though fairly well formed at birth, they are yet some- 

 what undeveloped. They rapidly increase in relative size and complexity, however, being 



