THE SUPRARENAL SYSTEM 2QQ 



The small portal system of the suprarenals was minutely in- 

 vestigated in different animal classes by S. Jourdain (1859). He 

 found that it was present, not only in Ophidians, but in Chelo- 

 nians, crocodiles and Saurians (Corti, 1847), thus in all the 

 reptilian orders. 



In this " Beitrage zur Entwickelungsgeschichte des Venen- 

 systems der Amnioten " (1892) F. Hochstetter gives a detailed 

 description of the suprarenal portal system in reptiles, together 

 with an excellent drawing showing the conditions in Lacerta 

 viridis. In a later work he describes the suprarenal portal system 

 in Crocodilus niloticus. 



In Batrachians (anura), according to Jourdain, the branches 

 of the vena renalis efferens, before uniting in the median line to 

 form the vena cava posterior, form long anastomoses and a series 

 of long arcades, which surround the yellowish bodies of the 

 suprarenal, and to some extent pass into the suprarenal tissue. 

 Jourdain does not, however, venture upon a decision as to whether 

 this arrangement constitutes a suprarenal portal system. Jourdain 

 found that, in Selachians, a small number of fine venous branches 

 led into the external layer of the suprarenal cortex, while the 

 median layer contained numerous veins leading into the venae 

 cardinales ; he believes that this represents a small portal system. 

 In Jourdain's drawings, the " suprarenals " are invariably asso- 

 ciated with arterial branches, but it is not possible to say whether 

 these suprarenals are interrenal bodies or whether they are adrenal 

 organs. The intimate association, in fish, between the suprarenal 

 system and the arterial and venous vessels, has been commented 

 upon by all the more recent investigators, but a suprarenal system 

 as such has not been described. 



A special interest is attaching to the conditions which obtain 

 in birds. The suprarenals are here furnished with two separate 

 veins upon both sides. Upon the median side of the suprarenal 

 that which is nearest to the vena cava is a comparatively short 

 and broad vein (vena suprarenalis interna), which opens into the 

 vena cava. Upon the lateral side of the organ is a second vein 

 (vena suprarenalis externa), the course of which is complicated. 

 In the majority of birds, the vena externa is formed by the union 

 of one or two dorsal intervertebral and intercostal veins, together 

 with a perforating dorsal cuticular vein. More rarely, a sacral 

 intervertebral vein and a vein from the upper suprarenal surface 

 empty themselves into the vena externa. As early as 1844, 

 Neugebauer foresaw the real significance of this vena externa. 

 The comparatively large size of the lumen at the place where the 

 vein enters the organ, together with the absence of a direct com- 

 munication with the vena interna, suggested to him the idea that 

 this vein might convey blood to the organ. 



A few years later, the existence of a vena afferens upon the 

 external surface of the suprarenal of birds was proved by Gratiolet. 



