56 



THE SUPKARENAL CAPSULES. 



In the Tunicata, this gland, represented by a groove, secretes a digestive fluid. In verte- 

 brates, it is an organ which has undergone a retrograde change (Gegenbaur). 



IV. The Suprarenal Capsules. Structure. These organs are invested by a thin capsule 

 which sends processes into the substance of the organ. They consist of an outer (broad) or 

 cortical layer and an inner (narrow) or medullary layer. The former is yellowish in colour, 

 firm and striated, while the latter is softer and deeper in tint. In the outermost zone of the 

 cortex (fig. 128, b), the trabecular form polygonal meshes, which contain the cells of the gland- 

 substance ; in the broader middle zone the meshes are elongated, and the cells filling them are 

 arranged in columns radiating outwards. Here the cells are transparent and nucleated, often 



containing oil-globules ; in the innermost narrow zone 

 the polygonal arrangement prevails, and the cells often 

 contain yellowish-brown pigment. In the medulla 

 (c), the stroma forms a reticulum containing groups of 

 cells of very irregular shape. Numerous blood-vessels 

 occur in the gland, especially in the cortex. [The 

 nerves are extremely numerous, and are derived from 

 the renal and solar plexuses. Many of the fibres are 

 medullated. After they enter the gland, numerous 

 ganglionic cells occur in the plexuses which they form. 

 Indeed, some observers regard the cells of the medulla 

 as nervous. Undoubtedly, numerous multipolar nerve- 

 cells exist within the gland.] 



Chemical Composition. The suprarenals contain 

 the constituents of connective- and nerve-tissue ; also 

 leucin, hypoxanthin, benzoic, hippuric, and tauro- 

 cholic acids, taurin, inosit, fats, and a body which 

 becomes pigmented by oxidation. Amongst inorganic 

 substances potash and phosphoric acid are most abun- 

 dant. 



The function of the suprarenal bodies is very ob- 

 scure. It is noticeable, however, that in Addison's 

 disease (" bronzed skin "), which is perhaps primarily 

 a nervous affection, these glands have frequently, but 

 not invariably, been found to be diseased. Owing to 

 the injury to adjacent abdominal organs, extirpation 

 of these organs is often, although not always, fatal ; 

 in dogs pigmented patches have been found in the skin 

 near the mouth. Brown Sequard thinks they may be 

 concerned in preventing the over-production of pig- 

 ment in the blood. 



[Spectrum. MacMunn finds that the medulla of 

 the suprarenal bodies (in man, cat, dog, guinea-pig, 

 Section of a human suprarenal capsule, rat, &c.) gives the spectrum of haemochromogen ( 18), 

 a, capsule ; b, gland-cells of the cortex while the cortex shows that of what he calls histo- 

 arranged in columns ; c, glandular net- hsematin, the latter being a group of respiratory pig- 

 work of the medulla ; d, blood-vessels. ents. He finds that haemochromogen is only found 



in excretory organs (the bile, the liver), hence he re- 

 gards the medulla as excretory, so that part of the function of the adrenals may be "to meta- 

 morphose effete haemoglobin or haematin into haemochromogen," and when they are diseased, 

 the effete pigment is not removed, hence the pigmentation of the skin and mucous membranes. 

 Taurocholic acid has been found in the medulla by Vulpian, and pyro-catechin by Krukenberg. 

 MacMunn believes that "they have a large share in the downward metamorphosis of colouring 

 matter. "] 



V. Hypophysis Cerebri Coccygeal and Carotid Glands. The hypophysis cerebri, or 

 pituitary body, consists of an anterior lower or larger lobe, partly embracing the posterior lower 

 or smaller lobe. These two lobes are distinct in their structure and development. The posterior 

 lobe is a part of the brain, and belongs to the infundibulum. The nervous elements are dis- 

 placed by the ingrowth of connective-tissue and blood-vessels. The anterior portion represents 

 an inflected and much altered portion of ectoderm, from which it is developed. It contains 

 gland-like structures, with connective-tissue, lymphatics, and blood-vessels, the whole being 

 surrounded by a capsule. According to Ecker and Mihalkowicz, it resembles the suprarenal 

 capsule in its structure, while, according to other observers, in some animals it is more like the 

 thyroid. Its functions are entirely unknown. [Excision. Horsley has removed this gland 

 twice successfully in dogs, which lived from five to six months. No nervous or other symptoms 

 were noticed, but when the cortex of the brain was exposed and stimulated, a great increase in 

 the excitability of the motor regions was induced, even slight stimulation being followed by 

 violent tetanus and prolonged epilepsy.] 



Fig. 128. 



