THE KIDNEY. 



20Q 





proper, which includes all the conventional subdivisions from the Malpighian 

 body to the termination of the distal convoluted tubule; and () the duct-tube, 

 which, when traced from the papilla towards the cortex, undergoes repeated 

 division until, from the single main 

 stem, the number of connecting tu- 

 bules is sufficient to provide each 

 uriniferous tubule proper with an 

 excretory canal. 



Details of the Uriniferous Tubule. 

 The general course and relations of 

 the tubule having been sketched, a brief 

 account of its more important structural 

 details may here find an appropriate place. 



i. The Malpighian body, irregularly 

 spherical and from .I2-.20 mm. in diam- 

 eter, consists of the glomerulus and the 

 capsule. The glomerulus is an aggrega- 

 tion of tortuous capillary blood-vessels 

 derived from the lateral terminal branches 

 given off from the cortical arteries as these 

 pass between the lobules towards the free 

 surface of the kidney. One of the lat- 

 eral branches.very short andoften arched, 



enters the adjacent Malpighian body as the vas afferens, where it divides into from four 

 to six twigs, each of which breaks up into capillaries. These may anastomose and form 

 a vascular complex, or each terminal twig may give rise to an isolated capillary territory, 



Capsule 



Efferent 

 vessel 



Intertubular 

 capillaries 



FIG. 257. Injected glomerulus, showing afferent 

 and efferent vessels and continuation of the latter 

 into the intertubular capillary network. X 180. 



Capsule 



Neck 



.Convoluted tubule 



111' 

 f^&zf+'i-j&i?- N 



_Vein 



Afferent arteriole 



Convoluted tubules 



FIG. 258. Section of cortex, showing details of a renal corpuscle or Malpighian body ; the glomerulus is 

 surrounded by capsule which passes into obliquely cut neck of tubule. X 200. 



the entire glomerulus then consisting of a group of vascular lobules. The channels of 

 exit unite to form the single vas efferens, through which the blood from the glomerulus 

 escapes. As the efferent emerges from the body, it is close to the afferent vessel, both 

 usually lying on the side opposite to that from which the tubule springs. The capsule, 

 the dilated beginning of the uriniferous tubule, almost completely invests the glomerulus 

 with a double layer, the prolonged wall of the tubule. The outer and inner layers are 



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