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Nachdruck verboten. 

 On the Relationship between the Thyroid and Parathyroids. 



By J. Halpenny, M. A., M. D., C. M. and F. D. Thompson i). 



(From the Physiological Laboratory, University of Manitoba, Winnipeg, 



Canada.) 



Preliminary Communication. 



With 4 Figures. 



The parathyroids were discovered by Sandström who believed 

 them to be composed of embryonic thyroid tissue, but the majority 

 of observers up to the time of Gley have held that there is no re- 

 lationship between them and the thyroid. 



Vincent and Jolly ^) describe the structural changes in parathy- 

 roids left behind after removal of the thyroid in the cat, and give 

 illustrations showing how, when left behind, parathyroid tissue approxi- 

 mates in appearance to ordinary thyroid tissue so that in some cases 

 the two are indistinguishable. Up to the present time we believe that 

 the drawings they give are the only ones published that illustrate 

 this fact. They conclude that when the thyroid is removed the para- 

 thyroids appear capable of functionally replacing it to a certain extent, 

 and their histological structure changes accordingly. Therefore the 

 thyroid and parathyroids are to be looked upon as a single physio- 

 logical apparatus, the two being intimately associated embryologically 

 and working together physiologically. It is a striking fact that there 

 appears to be no fundamental difference between their constituent cells. 



The parenchyma of the thyroid is by no means entirely composed 

 of vesicles, but there is a large and variable amount of inter vesicular 

 material, composed of masses of cells, which do not appear to diifer 

 from those lining the vesicles. This tissue seems identical with that 

 of the parathyroids. 



There seems to be no escape from the conclusion that in mam- 

 mals the thyroid and parathyroid tissues are related to each other and 

 that the connections are not only physiological but anatomical. 



From a dog both thyroid lobes and the two internal parathyroids 

 were removed, leaving behind the external parathyroids on both sides. 



1) The surgical proceedings have been carried out by Dr. Hal- 

 penny, and the histological preparations and drawings by F. D. Thompson. 



2) Journal of Physiol., Vol. 32, No. 1, Dec. 3, 1904. 



