THE VASCULAR GLANDS. 



masses of protoplasm, the differentiation of which into distinct cells cannot 

 be made out. (b) A layer of cells arranged radially, the zona fasciculata (c). 

 The substance of this layer is broken up into cylinders, each of which is 

 surrounded by the connective -tissue framework. The cylinders thus pro- 

 duced are of three kinds one containing an opaque, resistant, highly 

 refracting mass (probably of a fatty nature); frequently a large number 

 of nuclei are present; the individual cells can only be made out with diffi- 

 culty. The second variety of cylinders is of a brownish color, and con- 

 tains finely granular cells, in which are fat globules. The third variety 

 consists of grey cylinders, containing a number of cells whose nuclei are 

 filled with a large number of fat granules. The third layer of the corti- 

 cal portion is the zona reticularis (not shown in Fig. 258). This layer is 

 apparently formed by the breaking up of the cylinders, the elements being 



Fia. 259. Section through a portion of the medullary part of the supra-renal of guinea-pig. The 

 vessels are very numerous, and the fibrous stroma more distinct than in the cortex, and is moreover 

 reticulated. The cells are irregular and larger, clean, and free from oil globules. (S. K. Alcock.) 



dispersed and isolated. The cells are finely granular, and have no 

 deposit of fat in their interior; but in some specimens fat may be pres- 

 ent, as well as certain large yellow granules, which may be called pig- 

 ment granules. 



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

 meshwork of fibrous tissue, in the alveoli of which are masses of multi- 

 nucleated protoplasm (Fig. 259); numerous blood-vessels; and an abun- 

 dance of nervous elements. The cells are very irregular in shape and size> 

 poor in fat, and occasionally branched; the nerves run through the corti- 

 cal substance, and anastomose over the medullary portion. 



Function. Of the function of the supra-renal bodies nothing can be 

 definitely stated, but they are in all probability connected with the lym- 

 phatic system. 



