

Hl'.MAN ANATOMY. 



!'!<;. 1600. 



Capsule 



pi u hian body the tubule becomes very tortuous and arches towards the free surface 

 as the proximal convoluted tubule (2) ; this, after a course of considerable length 



usually leaves the labyrinth and 

 enters the medullary ray, which it 

 traverses, somewhat reduced in 

 diameter and slightly winding in 

 course, as the spiral tubule (3) and 

 passes into the medulla. Immedi- 

 ately upon gaining the latter, the 

 tubule suffers marked decrease in 

 size, penetrates the renal pyramid 

 for a variable distance towards the 

 papilla, then bends sharply upon 

 itself and retraces its course to once 

 more enter the labyrinth. Its ex- 

 cursion into the medulla includes 

 the descending limb (4) and as- 

 cending limb (5) of the loop of 

 Ilcnle. The ascending limb the 

 longer and wider of the parallel 

 limbs of the loop rises within the 

 labyrinth to the immediate vicinity 

 of the corresponding Malpighian 

 body, the neck of which it crosses, 

 and then, after arching over the cor- 

 puscle, gives place to the distal 

 convoluted or intermediate tubule 

 (6), a segment which, marked by 

 increased diameter and tortuosity, 

 crosses the general course of the 

 convoluted tubule and is succeeded 

 by the narrower and arching con- 

 necting tubule (7). The latter 

 enters the medullary ray and, join- 

 ing with similar canals, forms the 

 straight collecting tubu If ( S ), which, 

 progressively increasing in size by 

 junction with others, traverses the 

 remaining length of the medullary 

 ray and enters the renal pyramid. 

 Within the deeper part of the latter 

 the collecting tubules fuse into larger and larger canals until, as the relatively wide 

 papillary ducts 1 1> >. they terminate on the apex of the papilla at the orifices (fora- 

 mina papillaria > \\hich open into the calyces. 



The relations between the various segments of the uriniferous tubules and the 

 subdivisions of the kidney are. therefore, as follows : 



Section i -I iciitix. sli<i\\in K irlaimn of labyrinth 

 ami mriliillarv rays. X 50. 



Com i \ 



Labyrinth 



Medullary ray 



Mi Dl 1.1 \ 



Malpighian body, capsule and glomerulus 



Proximal convoluted tubule 



.Wending limb of Henle's loop 



Distal convoluted or intermediate tubule 



Connecting tubule (beginning > 



Connecting tubule (termination i 



Spiral tubule 



Collecting tubule 



Descending limb and 



Ascending limb of Henle's loop 



Collecting tubule 



Papillary ducts 



