Studies on the Endocrine C! lands 



341 



colloid is stained faintly red by hjematoxylin-eosin. The lining epithelium 

 is composed of cubical or Hattenud cells, the cytoplasm of which is usually 

 stained faintly by eosin. Some contain fine granules staining deeply red 

 with eo.sin. The nuclei of the epithelium cells are round or oval (5/i). 

 They are usually in the middle of the cell, and are always distinctly stained by 

 hsematoxylin. They contain tine chromatin granules. Between the vesicles 

 groups of epithelium cells are fre(juently to be seen ; in some cases this 

 may be due to the fact that the wall of a vesicle has been cut tangentially. 





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Fig. 2. — Sections showing adjacent portions of thyroid and parathyroid of male rat 

 fed with the addition of 1 grm. of dry ox-thyroid per diem to its ordinary food 

 during two periods of seven days, with a week's intennission. ^licrophotograph ; 

 magnified 200 diameters. Hiematoxylin-eosin {jrejiaration. 



The thyroid vesicles are full of colloid, distinctly stained. Their lining 

 epithelium cells are Hattened ; some of the vesicles contain debris of epithelium. 

 The te.\ture of the parathyroid has a loose appearance owing to marked 

 vaeuolation of the cells. 



Peiser described the free end of the epithelium cells as melting gradually 

 away into the colloid content of the vesicles; he states that the colloid 

 material appears to pass between the cells to the blood-vessels. I have 

 myself seen in some cases an appearance similar to that which Peiser has 

 described, but in most instances the epithelium cells appear quite distinct from 

 the colloid, and stain differently from it. There is, in point of fact, a w^ell- 

 marked boundary between the cytoplasm of the cell and the colloid sub- 

 stance, and it is probable that the other appearance is due to the junction 

 between the two being cut obliquely. 



With regard to the parathyroids. As was stated by Christian! (10) 

 and by Erdheim (11), there is usually in the rat only one parathyroid 



