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Note on the development of the Pharyngeal Bursa in the Ferret. 



By Marion Eadford. 



Anatomical Department, University of Birmingham. 



"With 6 Figures. 



In reading Professor Huber's comprehensive study " On the re- 

 lation of the Chorda Dorsalis to the xlnlage of the Pharyngeal Bursa^) " 

 it occurred to me that certain observations of my own on the condition 

 in a ferret embryo might be of some interest. I have therefore set 

 them down, incomplete as they are, seeing that few carnivores have 

 been studied from this point of view. 



They tend to confirm Meyer's belief that the median pharyngeal 

 recess is identical with Seessel's pocket and is not as Huber states an 

 entirely separate and distinct structure, almost exclusively confined to 

 humans. 



I will quote briefly the conclusions of those waiters who have 

 dealt with the problem. 



KiLLiAN^) finds a true pharyngeal bursa only in Arctomys Mar- 

 mota. He says "Ich betrachte also die Bursa pharyngea embryonalis 

 als eine wahre Ausstülpung der Eachenschleimhaut nach hinten und 

 oben gegen das Hinterhauptsbein, wobei speziell im Epithel das 

 formative Prinzip zu suchen ist." 



According to Killian, then, the pharyngeal bursa is an entirely 

 entodermic structure. He has not in any animal found it co-existing 

 with a pharj'ngeal tonsil and therefore considers it has no part in the 

 formation of the latter, as Schwabach thought it had. He lays stress 

 on the solid origin of the pharyngeal tonsil, which does not begin as a 

 hollow diverticulum. 



Mead,3) describing the condition in an embryo pig, shows the 

 anterior end of thenotochord opening into the pharynx and immediately 

 leaving it again to run forward and upward for a short distance to its 



1) Huber, Anatomical Record, Vol. 6, No. 10, 1912. 



2) Killian, Morphologisches Jahrbuch, Bd. 14, 1888. 



3) Mead, Amer. Journ. of Anat., Vol. 9. 1909. 



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