200 



NORMAL HISTOLOGY. 



converge to certain points, where they form the venae stellatae ; 



these veins afterwards pass into the labyrinth and follow the inter- 



lobular vessels. 



The arteries supply- 

 ing the medulla enter 

 as straight vessels, the 

 arteriae rectae, which 

 undergo repeated divis- 

 ion to form rich inter- 

 lobular net-works reach- 

 ing as far as the papillae, 

 where the orifices of the 

 excretory ducts are sur- 

 rounded by capillaries. 

 The blood within the 

 medulla is collected by 

 the venae rectae, which 

 accompany the corre- 

 sponding arteries and 

 empty into the large 

 veins situated at the 

 juncture of the cortex 

 and the medulla. The 

 large venous trunks 

 pass obliquely through 



Section of injected kidney of dog, showing general disposi- 

 tion of blood-vessels : a and b, large arterial and venous 

 branches situated at junction of cortex (C) and medulla (Af), 

 which break up into ascending intcrlobular twigs (c) and de- 

 scending straight vessels (/, F) ; e,f, afferent and efferent ves- 

 sels of glomeruli (g) ; h, intertubular capillary net-works ; z, 

 peripheral venous trunks, which collect the blood from sub- 

 capsular net-works (A). 



the medulla, along with 

 the arteries, to reach the 

 pelvis, where they join 

 with their fellows to form 

 the renal veins. 



The lymphatics of 

 the kidney are arranged as two sets of vessels ; a superficial sys- 

 tem ramifies within the deeper layers of the capsule, while a system 

 of deeper channels passes in company with the blood-vessels into 

 the interior of the organ to communicate with the numerous lym- 

 phatic clefts and spaces which exist within the intertubular connective 

 tissue. 



Regarding the ultimate distribution of the nerves of the kidney, 

 little is known with certainty beyond the fact that they enter the 

 parenchyma in company with the blood-vessels, around which they 

 form net-works of non-medullated fibres; the nerve-fibres have been 

 traced between the tubules, where they form meshes immediately 

 outside the membrana propria. The ultimate distribution of the 

 fibrillae and their relations to the secreting cells are still uncertain. 



