CHAPTER XXII 

 THE DUCTLESS GLANDS 



UNDER this heading it will be convenient to consider the supra- 

 renal, thyroid, parathyroid, carotid, and coccygeal glands, and the 

 hypophysis cerebri. 



I. THE SUPRARENAL GLANDS 



The suprarenal glands (adrenals) are two glandular masses situ- 

 ated above but in close relation with the upper extremity of each 

 kidney. On section the adrenal is seen to be readily divisible into 

 a bright yellow or brownish-yellow cortex and a more vascular, 

 and^ hence darker and somewhat reddish, medulla, whose central 

 portion transmits several large veins which make their exit from 

 an indentation in the anterior surface of the organ, known as the 

 Jiilum. 



The organ is inclosed by a connective tissue capsule of consid- 

 erable thickness. From the inner surface of the capsule delicate 

 fibrous trabeculae pass inward and subdivide the epithelial paren- 

 chyma of the organ into cell groups and columns, which vary in 

 their appearance according to the distribution of the connective 

 tissue trabeculae. The organ may be thus divided into a central 

 medulla and a peripheral cortex. In the medulla the connective 

 tissue presents an irregular areolar arrangement ; the more regu- 

 lar, though varying form of the areolae in the cortex, subdivides 

 this portion of the organ into three more or less distinct layers, 

 which were first described by Arnold * as the zona glomerulosa, zona 

 fasciculata, and zona reticularis. 



In the zona glomerulosa the connective tissue trabeculae sub- 

 divide the epithelium into spheroidal groups of cells, many of 

 which are continuous with the cell columns of the adjacent zona 

 fasciculata. The glomerulate layer is relatively thin and lies close 

 beneath the capsule. 



* Arch, f . path. Anat., 1866. 



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