PATHOLOGY OF THE THYROID. 



FUNCTION OF THE THYROID. 



The thyroid is a gland surrounded by a fibrous capsule 

 from which partitions arise which divide it in lobes. 

 Each one of these lobes contains a series of closed vesicles, 

 of various sizes, and without any excretory canal. 



The walls of the vesicles are lined with epithelium, made 

 up of two types of cells: the main cells, which have a 

 round nucleus with a clear protoplasm and colloidal cells, 

 which are polymorphous, have an oval nucleus and a 

 protoplasm filled with acidophil or basophil granulations. 



The cavity of the vesicle, oval, or spherical, contains 

 a thick secretion, more or less yellow, which has been 

 termed colloidal substance. 



The secretion of the thyroid is made up of several prod- 

 ucts, the most important of which contains iodine. 

 Chemists have extracted it from the colloid and Baumann 

 has designated it under the name of lodothyrin. We 

 know to-day that lodothyrin is only one of the compon- 

 ents of the thyroid secretion and that it is furthermore an 

 artificial product, not well defined, and made up of several 

 compounds. According to Oswald, the colloid contains 

 at least two substances : 1 A globulin or thyroglobulin 

 which contains all the iodine of the gland as an organic 

 compound and from which iodothyrin is derived; 2 

 A nucleo protein, which does not contain any iodine, but 

 instead other minerals, phosphorus and arsenic in particular. 



Iodine when introduced into the organism is fixed by 

 the thyroid. The quantity varies in each species and in 

 each individual according to the food. It cannot be con- 

 sidered as an index of the activity of the thyroid. 



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