ANATOMY, EMBRYOLOGY AND HISTOLOGY 63 



(Dreyer, confirmed by Stewart, Rogoff, and Gibson; denied by Gley and 

 Quinquaud(6)). 



Independence of tlie Cortex and the Medulla. That the two parts of 

 the gland are independent structures is indicated by a variety of observa- 

 tions and believed by most endocrinologists. As described in succeeding 

 paragraphs, they are distinct in embryonic origin. Moreover, we may get 

 aplasia of the cortex while the chromaphil tissue remains intact, as in 

 the case described by Apert, and conversely, the medullary substance was 

 found to be completely wanting in the five cases of congenital hydroceph- 

 alus described by Czerney. The cortical and the medullary substances, 

 therefore, vary independently. 



Relation of Cortex to Lipoid Formation. There is some reason to 

 believe that the growth of the cortex is related to that of the brain, and 

 especially to the development of its lipoid substance. "The suggestion 

 that the suprarenal cortex may be a seat of manufacture of the lipoids of 

 the body, and may especially be related to the formation and development 

 of the myelin of the medullated nerve fibers, is attractive. And the fact 

 that in the human fetus and infant so large a development of the supra- 

 renal cortex occurs which is missed in the anencephalous monster seems 

 to indicate a connection between the development of the substances formed 

 in the cortex and those constituting the cerebral hemispheres. But against 

 this idea, we have the observation of Elliott and Armour that the super- 

 added part of the suprarenal cortex in the fetus does not contain the doubly 

 refracting lipoid substances which are characteristic of the ordinary cor- 

 tical cells. Nor does the doubly refracting lipoid matter occur in all 

 animals; in many species it is absent. This is the case with all adult 

 ruminants examined, although it occurs in some in the young state." 

 (Quotation from Schafer(6).) 



Embryology 



The suprarenal glands, like the hypophysis, are developed from two 

 distinct sources, 



Origin of the Cortex. Soulie finds that the cortex first makes its 

 appearance in the embryo of six millimeters, i. .e, at the fourth week of 

 development. The cortical cells appear as a series of buds, which arise 

 from the celomic epithelium in the dorsal body wall. These buds grow 

 inward into the mesoderm and lie ventral to the aorta. At eight milli- 

 meters the glands are definitely separated from the parent tissue, and at 

 nine millimeters have acquired their own blood supply. Later, the buds 

 fuse and form a ridge of tissue projecting from the wall at the root of 

 the mesentery on each side just mesial to the mesonephros. The supra- 

 renal ridge thus formed extends as far forward as the dorsal pillars of 



