20 



The Endocrine Organs 



contain fatty granules, which increase in number with age ; glycogen has 



also been detected both in the cells and in the interstitial spaces of the gland. 



Vesicles containing colloid material similar to those of the thyroid, but 



usually smaller, are frequently found in the parathyroids. They usually 



increase in number with age, and 

 occasionally the colloid is found be- 

 tween the cells, not enclosed within 

 a vesicle. Whether it is of the same 

 chemical nature as that of the thyroid 

 is not established, but it is probably 

 different, as it appears to contain no 

 iodine. After complete removal of 

 the thyroid, in the parathyroids 

 which had been left colloid-contain- 

 ing vesicles were found by Vincent 

 and Jolly in considerable number 

 and of some size (fig. 14). This 



?x£.i c 



epilA c 



Fig. 14. — Section of parathyroid of cat after 

 previous removal of thyroid. (Vincent and 

 Jolly.) Vesicles which contain colloid are 

 developed within the gland. 



observation has been confirmed by Halpenny and Thompson, who found 

 that if the animal survives a sufficient time the vesicles become large and 

 irregular (fig. 15), 1 presenting a certain resemblance to those of a thyroid 



--— e. interves. 



Fig. 15. — Section of parathyroid of dog, eighty-three days after thyroidectomy. 

 (Halpenny and Thompson. ) The gland now contains a large number of irregular 

 vesicles and exhibits signs of hypertrophy and increased activity. 



e.veg., epithelium of vesicles; e.interves., epithelium between vesicles; c, colloid; eves., 

 cavity of vesicle. 



in exophthalmic goitre (fig. 26, p. 38). The same observers state that 

 after removal of all the parathyroids the vesicles of the thyroid tissue 



1 It is suggested by Guleke that the authors were here dealing not with a parathyroid 

 but with an accessory thyroid. The parathyroids usually remain unaltered in myxcedema : 

 Forsyth has, however, described one case which was an exception to this rule (Trans. Clin. 

 Soc, 1907). Biedl has also recorded the development of colloid-containing vesicles in the 

 parathyroid in a case of atrophy of the thyroid in man. 



