THE ADh'EXAL C LANDS 



259 



iiiaintenaiicc of the iiitroi^cn fciuilihriuin, and I'oniiatioii of hone 

 and dentin. Proper com})ination of parathyroid secretion and cal- 

 cium salts is essential to normal muscle contraction and administra- 

 tion of parathyroid extract relieves tetany dxw to faulty function 

 of the ])arathyroids. Entire removal of ])arath\r()i(ls results in 

 death. 



3 



Cords of cells separated 

 by capillaries 



Fig. 160. — Diagram of iiianimalian parathyroid, showing capillaries between the cords 



of cells. 



THE ADRENAL GLANDS. 



In quadru])ed manunals, one of these glands is located at the 

 anterior end of each kidney. In man they are called suprarenals, 

 because they are located at the up])er end of the kidneys. They 

 have no known functional connection with the kidneys. In man 

 they are somewhat flattened, small bodies, the right one being tri- 

 angular in form, the left somewhat crescent-shaped. In other 

 mammals they are bean-sha])ed masses, embedded in adi])ose tissue 

 which tends to form near the kidneys. The adrenals are exceedingly 

 well sui)i)lied with blood vessels and it has been estimated that 

 blood to the amount of about five times their weight circulates 

 through them every minute. They are surrounded by a firm capsule 

 of connective tissue, extensions of which pass into the interior of 

 the gland. Cross-sections of fresh adrenal glands made with 

 a sharj) knife reveals an outer cortical zone, light yellow in color 

 and of firm textiu"e, siu'rounding a central medullary region of looser 



