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A TEXTBOOK OF PHYSIOLOGY 



within the uterus, probably by maintaining an increased metabolism 

 of the uterus during the early stages of pregnancy. The corpus 

 luteum also furnishes, in the initial stages of pregnancy, an internal 

 secretion which stimulates development of the mammary gland. 



The Suprarenal Bodies. Each suprarenal gland consist of a cortex 

 and a medulla. The cortex, the cells of which are arranged in charac- 

 teristic columnar fashion, is derived from the mesoblast associated 

 with the urogenital system, the Wolffian ridge. The medulla is of 

 nervous origin, and its cells are arranged in strands which enir.esh 

 lacunar veins. Many of these cells are characterized by their affinity 

 for chromium salts, and are therefore known as chromophil cells. 

 Such chromophil cells are also found in the ganglia of the sympathetic 



FIG. 242. SECTION THROUGH \ GROUP OF CHROMOPHIL CELLS IN INFERIOR CERVICAL 

 GANGLION OF A DOG. (Swale Vincent.) 



nervous system, and in accessor} 7 suprarenal masses which are often 

 found connected with the abdominal ganglia of this system (c/. Fig. 242). 



Little is known concerning the function of the cortex of the supra- 

 renal glands, but it has been suggested that it interacts with the sexual 

 glands influencing the acquirement of sex characters. In many cases 

 of sexual precocity an abnormal development of the cortex of the 

 suprarenal has been found. 



Far more evidence has been obtained as to the function of the 

 medulla of the suprarenal, which appears to be of great importance 

 to the organism. Addison long ago pointed out that the fatal disease 

 known by his name was always attended by, and therefore probably 

 due to, disease of the suprarenal glands. The disease is characterized 

 by these symptoms: a gradual increasing muscular weakness, bronzing 

 of the skin, and vomiting. 



