410 



THE KIDNEYS. 



Fi-. 294. 



epithelium dips down between the bunches. The basement, membrane, 

 both of the capsule and of the uriniferous tubule, is formed of flat 

 epithelioid cells (fig. 293, a, a'). 



Blood-vessels. — The 

 kidneys are highly vascu- 

 lar, and receive their blood 

 from the renal arteries, 

 which are very large in 

 proportion to the size of 

 the organs they supply. 

 Each renal artery divides 

 into four or five branches, 

 which, passing in at the 

 hilus, between the vein 

 and ureter, may be traced 

 into the sinus of the 

 kidney, where they lie 

 amongst the infundibula, 

 together with which they 

 are usually embedded in 

 a quantity of fat. Pene- 

 trating the substance of 

 the organ between the pa- 

 pilla?, the arterial branches 

 enter the cortical substance 

 found in the intervals be- 

 tween the pyramids of Mal- 

 pighi, and proceed in this, 

 accompanied by a sheath- 

 ing of areolar tissue, and 

 dividing and subdividing, to reach the bases of the pyramids, where 

 they form arches between the cortical and medullary parts, which how- 



-Section 

 Human 



OF CoRTicAii Substance of 

 F(ETus. Highly magnified 



Fig. 294.- 



Kidney 



(Klein). 



a, glomerulus with blood-vessels not fully de- 

 veloped ; c, eijithelium covering it continuous with d, 

 flattened epithelium lining Bowman's capsule ; /, /, 

 convoluted tubes. 



Fig. 295. 



Fig. 295. — Diagram showing the Relation of the 

 Malpigiutan Body to the Uriniferous Ducts and 

 Blood-vessels (after Bowman). 



a, one of the interlobular arteries ; a' afferent artery 

 passing into the glomerulus ; c, capsule of the 

 Malpighian body ; t, uriniferous tube ; e\ c', efferent 

 vessels which sulxlivide in the plexus p, surrounding 

 the tube, and finally terminate in the branch of the 

 renal vein, c. 



ever are not complete, and in this respect 

 differ from the freely anastomosing venous 

 arches which accompany them. From the 

 arches smaller "interlobular" arteries (fig, 

 29G, ai) are given off", wliich pass outwards 

 between the double layers of Malpighian 

 capsules which intervene between the pyramids of Ferrein ; and from 

 these interlobular arteries are derived the afferent arteries of the 

 glomeruli. The renal arteries give branches likewise to the capsule 

 of the kidney which anastomose with branches of the lumbar arteries, 

 and that so freely that Ludwig was able partially to inject the kidneys 



'© t*', 





