214 



E. V. COWDRY 



Wells (&)) Under certain conditions they are said to give rise to adeno- 

 mata. According to Vincent (a) and others, they resemble closely the cells 

 of the parathyroid glands, and it is claimed that they increase in number 

 after parathyroidectomy ; but as yet no detailed comparison has been made 

 with the aid of methods adapted to the demonstration of mitochondria and 

 other details of cytoplasmic structure. Pending further information, it 

 is, therefore, unsafe to base generalizations upon this questionable analogy. 

 Certain it is that these cells and those of the parathyroids develop from 

 different embryonic anlagen. 



Fig. 4. Section of human thyroid gland with rather lobulated follicles completely 

 filled with optically homogeneous colloid substance. Note the desquamation of cells 

 into the follicular cavity (magnification 900). 



Other Interfollicular Cells. Small clusters of lymphocytes and even 

 fragments of thymus IV (see section on Parathyroids) are quite often 

 found in the intervesicular tissue ; the latter usually in association with the 

 glandulse parathyroidese IV. Small cavities, lined with ciliated epithe- 

 lium, occasionally occur also in the same location. 



Colloid Morphology. The colloid material is stored within the fol- 

 licles. As seen in fresh preparations it is a clear viscid substance. In 

 well fixed tissues it stains strongly with eosin and occupies the entire 

 vesicular cavity. It is said that a small fraction of it is basophilic (see 

 p. 215). In sections it frequently presents a vacuolated appearance in- 

 dicative, perhaps, of variations in density or of droplets of other material. 

 Jackson describes the production of these vacuoles through the solution of 



