THE RENAL CIRCULATION 



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ventr. 



fig. 2. Horizontal section through the dog kidney. RI and 

 RII. renal artery and primary branches; Arc I and Arc II: 

 primary and secondary arcuate arteries; IL: interlobar artery; 

 ILl: interlobular artery; Caps: capsular artery, U: aorta. [After 

 von Kiigelgen et al. (322).] 



100 to 150 ii in diameter, form a plexus which supplies 

 the calycine mucosa and the renal papilla (fig. 4). 

 Baker contends that they anastomose with the vasa 

 recta. It is important to emphasize that these vessels 

 participate with the vasa recta system (vide infra) in 

 supplying blood to the papillary zone containing the 

 tips of the loops of Henle, the site of maximal osmotic 

 concentration. Their long, coiled length delivers blood 

 into the vasa recta system at low pressure (6). Arterio- 

 arterial anastomoses occur in this system, an exception 

 to the usual pattern of end arteries found in the 

 divisions of the renal artery. 



Venous System 



Deferring discussion of the glomerular and capillary 

 circulation, attention is directed to the venous 

 system in figure 5. Note the sparsity of interlobular 

 veins relative to the interlobular arteries (a ratio of 

 20 to 1). Their function appears to be to connect the 

 superficial and deep venous systems of the cortex (V. 

 corticalis superficialis and V. corticalis profunda), 

 into which the capillaries drain. The upper fifth of 

 the cortex appears to be an "arterial-free'" zone (af 

 in fig. 5), so that the upper glomeruli are overlayed by 

 only venous channels (stellate veins, superficial 

 cortical veins), and prevenous capillaries (cortex 

 corticis). Puncture of glomeruli for this reason has 

 been unsuccessful in the dog. A "venous-free"' zone 

 (vf) also exists, free of cortical veins (superficial and 

 deep), and occupied only by occasional interlobular 

 veins. 



venous sinuses; veno-venous anastomoses. Venous 

 sinuses or sinusoids lying in the connective tissue 

 adjacent to the pelvis of the human kidney were 

 observed by Spanner (290, 291) and by Barrie 

 et al. (12). Spanner described them as isolated 

 accumulations of large venous plexi arranged super- 

 ficially along the walls of the minor calyces of the 

 renal pelvis. Trueta el al. also described in the same 

 zone of the human kidney many vessels of large caliber 

 which unite interlobar veins (veno-venous anasto- 

 moses). These vessels lie closely adjacent to the outer 

 surfaces of the walls of the calyces of the renal pelvis, 

 and the capillaries of the pelvic mucosa drain into this 

 complex system. They may offer a clue to the phenom- 

 enon of pyelovenous backflow sometimes seen after 

 retrograde pyelography. Veno-venous anastomoses 



fig. 3. Scheme of the finer arterial supply 

 of the dog kidney, gl: Glomerulus with vas 

 afferens. [After von Kiigelgen et al. (322).] 



