338 



THE DUCTLESS GLANDS 



CH. XXIII. 



The general idea, however, that prevails is that the thyroid 

 supplies something which is a stimulator of metabolic processes, and 

 that the action on the nervous system is more especially the work of 

 the parathyroids. 



The Supra-renal Capsules. 



These are two triangular or cocked-hat-shaped bodies, each resting 

 by its lower border upon the upper border of the kidney. 



The gland is surrounded by an outer sheath of connective-tissue, 



FIG. 315. Vertical section through part of the cortical portion of supra-renal of guinea-pig. , Cap- 

 sule ; 6, zona glomerulosa ; c, zona fasciculata ; d, connective-tissue supporting the columns of the 

 cells of the latter, and also indicating the position of the blood-vessels. (S. K. Alcock.) 



which sends in fine prolongations forming the framework of the gland. 

 The gland tissue proper consists of an outside firmer cortical portion 

 and an inside soft, dark medullary portion. 



(1.) The cortical portion is divided into (fig. 315) columnar groups 

 of cells (zona fasciculata). Immediately under the capsule, however, 

 the groups are more rounded (zona glomerulosa), while next to the 

 medulla they have a reticular arrangement (zona reticularis). The 

 cells themselves are polyhedral, each with a clear round nucleus, and 

 often with oil globules in their protoplasm. The blood-vessels run in 

 the fibrous septa between the columns, but do not penetrate between 

 the cells. 



(2.) The medullary substance consists of a coarse rounded or 

 irregular meshwork of fibrous tissue, in the alveoli of which are 



