THE KIDNEYS. 



1885 



straight twigs (arterioles rectcs) that at first surround the groups of collecting tubules and then 

 break up to take part in forming the capillary net-work of the medulla. From these meshes the 

 blood is collected by the straight venous radicles that accompany the arterioles and, with the 

 latter, constitute the vasce rector, owing to whose presence the darker stria; of the medulla are due. 

 In consequence of numerous anastomoses the vascular supply of the medulla is less independ- 

 ent of that of the cortex, than was formerly supposed (Huber). 



Veins. — The veins of the kidney are also disposed as cortical and medullary- 

 branches which empty into larger stems iyVence arciformes) that cross the bases of 

 the pyramids as a series of communicating" venous arcades. 



The blood within the cortical capillaries escapes by three paths : ( i ) through numerous 

 small veins that traverse the outer third of the cortex towards the capsule, beneath which they 

 empty into larger stems running parallel to the free surface of the kidney. From three to 

 five of these horizontal ves- 



FiG. 1 612. 



Capsule 



sels converge towards a com- 

 mon point and thereby pro- 

 duce a star-like figure {vena 

 stellata), which is the begin- 

 ning of the interlobular vein 

 that, in company with the cor- 

 responding arteriole, passes 

 through the cortex to become 

 tributary to the venous arcade 

 at the base of the pyramid ; 

 (2) through small venous 

 branches that empty directly 

 into the interlobular veins at 

 various levels ; (3) through 

 the deep cortical veins that 

 traverse the inner third of the 

 cortex and are tributaries of 

 the vence arciformes. The 

 medulla is drained by the ven- 

 ulcT rectce, straight x'essels 

 that begin in the medullary 

 capillary net-work and empty 

 into the arciform veins. The 

 latter terminate in the larger 

 interlobar veins that accom- 

 pany the arteries along the 

 sides of the pyramids and 

 emerge into the sinus around 

 the papillae. The further 

 course of the relatively large 

 and valveless venous trunks 

 corresponds with that of the 

 arteries ; the veins draining 

 each half of the kidney unite 

 into a single stem, the two 



thus derived joining to form the renal vein. The latter usually lies anterior to the renal artery in 

 its path to the vena cava, the left vein being longer than the right in consequence of the position 

 of the cava on the right of the spine. 



Stellate 

 vein 



Connecting 



vein 

 Capillary 



net-work 

 Interlobular 



vein 



Connecting- 

 vein 



Straight 

 vein 



Interlobar 

 vein 



Efferent 

 vessel 



Afferent 

 vessel 



Interlobular 

 artery 



Connecting 

 vein, to 

 medulla 



Straight 

 artery 



Interlobar 



vein 



Interlobar 

 artery 



Medullary 

 arterioles 



Capillary net-w 



Papilla 

 Diagram showing arrangement of blood-vessels of kidney. {After Disse.) 



The lymphatics of the kidney occur as a superficial and a deeper net-work. 

 According to the investigations of Stahr^ and of Cwneo,^ the superjicial lymphatics 

 comprise a delicate subcapsular mesh-work from which two systems of collecting 

 trunks arise ; the one passes into the kidney to join the deeper lymphatics within the 

 renal substance, the other pierces the capsule to unite with the perirenal lymphatics 

 within the capsula adiposa. The deep lymphatics arise within the cortex from deli- 

 cate interlobular net-works, the general path of the more definite stems being that of 

 the blood-vessels. On leaving the hilum, the larger collecting trunks — from four to 



^ Archiv f. Anat. u. Entwick., 1900. 

 ^ Bull. d. Soc. Anat, F^v. 1902. 



