THE SUPRARENAL BODIES. 



223 



Capsule 



Cortex 



The suprarenal body is invested by a distinct fibrous capsule, from which 

 delicate septa pass into the organ, forming a framework of connective tissue 

 for the support of the blood-vessels and the cellular constituents. Section 

 across the thicker parts of the body displays an outer zone, the cortex, from 

 .25-1.25 mm. in thickness, which encloses a central area, the medulla. 

 Towards the borders of the organ, the medulla is reduced to a narrow zone, 

 or may be entirely wanting; where best developed, as in the middle, it may 

 attain a thickness of over 3 mm. The cortex is usually of a dirty yellow color, 

 next the medulla presenting a 

 narrow band of varying shades 

 of brown. The medulla is of 

 a grayish tint and generally 

 lighter than the cortex. Its 

 exact color, however, varies 

 with the amount and condition 

 of the contained blood, when 

 engorged with venous blood 

 being dark. Embryology and 

 comparative anatomy indicate 

 that the mammalian supra- 

 renal body includes two en- 

 tirely distinct organs, which, 

 although intimately united 

 as the cortex and medulla, 

 possess different origins and 

 functions. The cortex arises 

 in close relation with the 

 Wolffian body, the foetal ex- 

 cretory gland, and later 

 migrates into secondary rela- 

 tion with the kidney. The 

 medulla is derived from the 

 adjacent embryonic sympa- 

 thetic ganglia, the medullary 

 cells closely corresponding 

 with the chromafnn elements 

 elsewhere originating from 

 the sympathetic. 



The cortical substance 

 consists of a delicate frame- 

 work of connective tissue, prolonged from the capsule, in whose meshes lie 

 the tracts of the distinctive epithelial cells. The cortex is not always uniform, 

 but often subdivided into indistinct subcapsular lobules by thicker septa con- 

 tinued from the overlying fibrous investment. The arrangement of the cortical 

 cells, although in a general way columnar or slightly radial in the peripheral 

 lobular areas, varies at different levels, three zones being distinguished within 

 the cortex (Fig. 274). The narrow zona glomerulosa lies next the capsule and 

 consists of rounded masses of somewhat tortuous groups of cells. The zona 

 fasciculata forms the major part of the cortex and is made up of parallel or 

 slightly radially disposed cell-columns. The zona reticularis, next the medulla 

 and narrow, includes the networks of epithelial elements formed by the union 

 of the inner ends of the columns of the preceding zone. The cells through- 

 out the cortical strands are fairly similar, being rounded polygonal elements, 



Capsule 



FIG. 273. Section of suprarenal body including entire thick- 

 ness of the organ, showing the general arrangement of cortex 

 and medulla. X 27. 



