THE PAEATHYKOID GLAND AND ITS DISEASES 505 



columns or clumps, separated, to a greater or lesser extent, by bands of 

 connective tissue, which are continuous with the capsule. 



Considerable variation is met with in the grouping of the gland cells, 

 even in different parts of the same organ. Sometimes they form an 

 almost solid mass with but little interstitial tissue ; occasionally, however, 

 the reverse is true. Quite frequently the cells show a tendencv to group 

 themselves into well defined follicles, as in the thyroid gland, which may 

 even contain colloid substance; or it may happen that colloid material is 

 distributed between cells not so arranged. The relation of this colloid to 

 the colloid of the thyroid gland is 

 not well understood. According to 

 Schafer, it does not contain iodin. 



Cytology. Two types of glan- 

 dular cells are usually recognized 

 in the parathyroids, the prin- 

 cipal cells and the oxyphil cells. 

 The principal cells are by far the 

 more numerous, making up .the 

 mass of the tissue, and are charac- 

 terized by their clear cytoplasm 

 and faintly staining nuclei. The 

 cytoplasm of the oxyphil cells, on 

 the other hand, stains strongly with 

 eosin and their nuclei intensely 

 with hematoxylin. They have a 

 pyknotic appearance and are gen- 

 erally thought to be undergoing de- 

 genera tion in the later stages of 

 cytomorphosis, similar to that of 

 the colloid cells of Langendorff in 

 the thyroid. This idea is supported by the fact that they do not make 

 their appearance until nine or ten years of age. 



Cell Inclusions. Glycogen is found in both types, but rather more 

 abundantly in the principal cells. It has also been described between the 

 cells. Fat is deposited within the cells during the first month after birth 

 and increases in amount with age. Mitochondria have been described in 

 the principal cells by Bobeau (a) (fr), who claims that they are trans- 

 formed into secretion. He bases his conclusion entirely upon a corre- 

 spondence in the distribution of the mitochondria and certain lipoid-like 

 droplets in the cells. He demonstrated the mitochondria, by methods which 

 he does not specify, and the lipoid by the method of Ciaccio. He assumes 

 that the lipoid droplets constitute a precursor of the secretion, or rather the 

 secretion itself, and that they arise through a swelling up of the mito- 

 chondria. 



Fig. 6. Human parathyroid. Note the 

 close association of the cell columns with 

 the blood vessels (magnification 720). 



