SUPRARENAL GLANDS 405 



In accordance with this conception he named the structures "atrobiliary capsules," 

 and the name capsule is still often applied to them. Diemerbroeck (Anatome, 1672), 

 following Wharton, states that "the glands are found at a place where there is a 

 plexus of nerves, to which they are firmly united." In reviewing the various "con- 

 jectures" as to their function, he writes, "Wharton thinks that in these capsules a 

 certain juice is removed from the plexus of nerves on which they lie, useless indeed to 

 the nervous system, but which, flowing thence into the veins, may serve some useful 

 purpose." The intimate relation of these glands to the nervous system, and the 

 production of an internal secretion received by the veins, have since been demon- 

 strated; in certain recent works the glands have even been described as parts of the 

 nervous system. Diemerbroeck concludes by hoping that physicians, through 

 many autopsies, may find out to what diseases these glands give rise. In 1855, 

 Addison described the disease, usually fatal, which is thought to depend upon the 

 loss of function of these glands. Their physiological importance has been amply 

 demonstrated, but they still present fundamental problems, both as to function and 

 structure. 



A section through a fresh suprarenal gland reveals at once the division 

 into cortex and medulla. The cortex is yellowish, owing to the presence 

 of lipoid substance, and the medulla is dark brown, due in part to the large 

 amount of blood which it contains. The color con- 

 trast is usually very striking, and it is shown also 

 in unstained sections of tissue preserved in chromic 

 acid solutions (Fig. 418), although the medulla may 

 then be lighter than the cortex. Not only do the 

 cortex and medulla differ in gross appearance, but 

 they are radically different in embryonic origin, and 

 in the sharks they exist as separate organs. In sharks 

 the medulla is represented by groups of chromafnn 

 cells associated with the sympathetic ganglia, and the 

 cortex takes the form of an "interrenal gland," 

 composed of cords of mesodermal cells with a sinu- 



Cortex. Medulla. 



soidal circulation. Inhuman embryos correspond- FIG. 418. SECTION OF THE 



. , . , SUPRARENAL GLAND OF 



ing parts arise separately, but they come together to A CHILD, x 15. 

 form a single gland. 



The cortex appears first, and is formed from cells which develop as buds 

 of the ccelomic epithelium, growing into the mesenchyma on either side of 

 the root of the mesentery, medial to the Wolffian bodies. In embryos of 

 8-12 mm., the buds or cords have become detached from the peritoneal 

 epithelium (Zuckerkandl), and in cross sections they appear as round 

 masses of cells penetrated by a network of slender veins. The cells 

 of these masses rest directly against the vascular endothelium, so that 

 the vessels are described as sinusoids. 



Meanwhile cells from the sympathetic ganglia grow ventrally along 

 the medial side of these masses, where they are conspicuous because of 

 their dark stain (Fig. 419). These cells, which give rise to the medulla of 



