592 



THE TISSUES. 



Fig. 419. 



considerably up to the 2d year. Subsequently it becomes atrophied, 

 and finally disappears, as above mentioned. 



IY. THE SUPKA-RENAL GLANDS. 



These bodies are usually classed with the blood vascular glands, 

 though they do not strictly belong to this class. They consist (1,) 



of a fine, but thin coat of areolar tis- 

 sue, and (2,) the proper parenchyma. 

 The former needs no special descrip- 

 tion. 



The parenchyma is divisible into two 

 parts, the cortical and the medullary 

 portions. (Fig. 419.) 1. The former is 

 of a whitish-yellow color (more nearly 

 brown in its innermost third), -$ to 

 24 of an inch thick ; easily torn in the 

 direction of its thickness, and when 

 torn, presenting a fibrous aspect. 



2. The medullary substance is of a 

 brighter color than the cortical, being 

 grayish -white with a tinge of red, 

 though it may become darker when 

 its veins are full of blood. It is softer 

 than the cortical substance, and only 

 i\ to 3*8 of an inch thick at their bor- 

 ders; while it is 1 to 1J line in the 

 middle, and the lower and inner half 

 of these organs. 



In their intimate structure the cor- 

 tical and the medullary portions are 



entirely dissimilar. The cortical substance consists of very nu- 

 merous compartments (cortical cylinders, Kollilcer), ^\Q to even 

 J^TS of an inch across, formed by interlacements of areolar tissue, 

 and extending through the entire thickness of the cortex ; contain- 

 ing a granular substance, subdivided by delicate, oblique, or trans- 

 verse dissepiments. (Fig. 420.) These generally contain nothing 

 but rounded angular cells, 2T \nF to roW f an i n h i n diameter. 

 In the inner brown layer of the cortex, the cells are entirely filled 

 with brown pigment-granules. 



The medullary substance also has a stroma of areolar tissue pro- 



Transverse section of the supra-renal 

 body of the calf, treated with soda. a. 

 Cortex. . 6. Medulla, c. Central vein, 

 surrounded with some cortical sub- 

 stance, d. Three entering nerves, e. 

 Serves and their distribution in the in- 

 terior. (Magnified about 15 diameters.) 



