I 



Structure of Suprarenal Capsules 51 



animal than in the adult, in which they may be missed altogether. The 

 possibility of their presence must, however, be borne in mind when con- 

 sidering the results of the extirpation of the adrenals in animals. 



Those accessory glands which have a structure and derivation similar 

 to the medulla of the suprarenal capsules also contain cells which are 

 coloured brown by chromic acid. Such bodies have been termed para- 

 ganglia by Kohn, chromaphil bodies by Vincent, chromaffine bodies by 

 most other authors. 



The carotid gland is of this nature. The coccygeal gland is different. 

 It contains no chromaphil cells and appears to represent an arteriovenous 

 anastomosis which is met with in certain lower mammals. Paraganglia in- 

 variably occur in close morphological and developmental connexion with 

 sympathetic nerves and ganglia (Stilling). 



Chromaphil cells have been found in almost all vertebrates, even in 

 Petromyzon. They have also been described in the epithelium cells of the 

 mantle of a gasteropod {Purpura lapillus) by Roaf. In Annelids they 

 occur, according to Sommet and Pol, in some of the nerve-cells of the 

 segmental ganglia. This is well seen in the leech, the blood-vessels of 

 which react to adrenalin like those of vertebrates. The development of 

 chromaphil cells is, according to J. F. Gaskell, correlated with that of a 

 muscular vascular system. 



Abel has made the interesting observation that certain patches of skin 

 glands in a large American toad (Bufo agua) furnish a white, pasty 

 secretion containing a large proportion of adrenalin. 



Structure of the Cortex 



The cortex of the suprarenal is composed of polygonal epithelium-like 

 cells arranged mainly in columns (zona fasciculata), but near the medulla 

 as a network of trabecular (zona reticularis). Towards the surface the 

 cell-columns end in rounded and sometimes hollowed-out terminations 

 forming the so-called zona glomerulosa, the cells of which, in some animals, 

 tend to have a columnar form. Those of the zona fasciculata are usually 

 larger than in the other parts. Characteristic of the cortical cells is the 

 presence of lipoid granules, which may impart a yellowish colour to this 

 portion of the capsule. The zona reticularis also contains pigment granules 

 which in some animals give it a distinct brownish colour. The human 

 foetus has unusually large suprarenal capsules. It has been shown that 

 this is almost entirely due to a great development of an innermost part of 

 the cortex lying at the boundary with the medulla (boundary zone of 

 Elliott and Armour (fig. 33)); this is not to be confounded with the 

 intermediate zone of Virchow, a very thin layer, pigmented in old ace, 

 lying at the junction of the cortex and medulla. 



The cells of the boundary zone differ from those of the rest of the cortex 

 in having no lipoid granules. After birth they undergo a fatty change 



