52 



The Endocrine Organs 



and the layer gradually disappears, so that it is no longer distinguishable 

 after the first year. At birth what will be the cortex of the adult gland 

 consists only of a thin peripheral layer of cells containing lipoids ; these 

 cells multiply, and the layer enlarges pari passu with the disappearance of 



':','..- 



FIG. 33. Section of suprarenal of child twelve days old, low power. (Elliott and Armour.) 



A, outer part of cortex ; B, large cells forming boundary zone of cortex ; C, thin layer of 

 medulla : just below is the central vein. 



the boundary zone. A remarkable fact pointed out by Elliott and Armour 

 is that in the anencephalous foetus the boundary zone is absent and the 

 suprarenal resembles that of other foatal mammals. 



FUNCTIONS OF THE CORTEX 



Little is known regarding the functions of the cortex. Its anatomical 

 relation in mammals to the chromaphil part and the fact that its blood 

 passes directly into the medulla suggests that its cells may be concerned 

 in the production of materials which are utilised by the medulla ; but, as 

 has been above mentioned, this relation fails in many vertebrates. It has 

 been stated by Abelous and others that the cortex contains a precursor of 

 the adrenalin of the medulla, and that if left standing for twenty-four 



