ANATOMY OF THE ADRENALS - ADDISON'S DISEASE AND OTHER The Supra-renal Capsules * are classified amongst the ductless glands of the body, in common with the spleen, thyroid and thymus glands. These have no excretory ducts. They lie at the back of the abdomen, surmounting each kidney, attached to it by connective tissue, and are behind the peritoneum. They are somewhat triangu lar in form, flattened from before backward. The right one is shaped like a cocked hat, but the left is somewhat semilunar, and is larger than the right one.
They measure from an' inch and a quarter to nearly two inches in length, are less in width, and are two to three lines in thickness. They weigh from one to two drachms each. During the earlier months of foetal life, the adrenal bodies preponderate greatly in size as compared with the kidneys. This relative proportion tends grad ually to diminish toward the end of intra-uterine life, but even then they appear large in comparison with the kidneys. The late Profes sor Allen Thomson, of Glasgow, was of the opinion that the prepon derance of the adrenals in foetal life was peculiar to the human sub ject, and not met with in any other mammalian animals.
These bodies are believed by some writers to be of larger size in swarthy than in fair races. This is an error, and the fact is estab lished that there is no noteworthy difference as to size or structure of the supra-renal capsules in the dark or white races of mankind.
The adrenal bodies, although large in early foetal life, and smaller by far at the time of birth, yet continue to grow with the growth of the body up to the time of adult age.
Before puberty these bodies are firm and partially translucent at the edges, and they contain a minimum amount of fat at this period. In the adult they are less firm, and never translucent in health; the amount of fatty matter is greater, and appears to go on increasing in advanced life (see p. 27).
The stroma of the glands is formed by prolongations from the outer investing sheath of connective tissue.
On section of healthy glands, there are at once apparent an outer and au inner portion. The outer is termed the cortical, and the in
ner the medullary portion. The cortical layer is of a yellowish color, the medullary of a pearly aspect, and after exposure to the air this portion is found to become somewhat pink in hue. In the laf.ter may be seen sections of blood-vessels, arteries, and veins.
Three zones are described in the structure of the cortex. The ex ternal one is a layer of closed vesicles, the zona glomerulosa. The vesicles contain a few small cells and a finely granular grayish mate rial, but no fat-globules.
The middle layer, the zonafascicu/ata, is composed of cylinders in vested with a stroma of connective tissue. These tubules are of three kinds, one set containing an opaque refracting mass, probably fatty, and indistinctly appreciable cells with numerous nuclei. A second variety of tubule is of brownish color, composed of finely granular cells containing fat-globules. The third variety consists of gray tubules, filled with cells whose nuclei contain fat-granules. These cylinders measure about of an inch in diameter.
The third layer of the cortex, the zona reticularis, is formed by the breaking up of the tubules and the dispersion of their contained elements. The cells are finely granular, and may have no deposit of fat in their interior; but sometimes fat is present, together with large yellow granules, seemingly pigmentary in nature.
The medullary portion consists of a reticular stroma containing groups of irregularly shaped cells. These closed vesicles are not ar ranged in tubular fashion, and this portion presents a marked con trast to the structure of the cortex. There are elements of the corti cal substance, and abundant nervous structures. The cells are poor in fat, and occasionally branched, resembling multipolar nerve-cells. The nerves pass through the cortex, and ramify in anastomosis through the medullary portion. The cells of the medulla are regarded by some observers as nervous, and there are certainly true multipolar nerve-cells among them.