KIDNEYS. 



423 



and the cells have an oval nucleus (Fig. 241). This changes to 

 a thick polyhedral epithelium, with a fibrillar or striated structure, 

 in the proximal convoluted tubule and spiral tubule of Schachona. 

 It is again flat in the descending limb of Henle's loop, while in 

 the ascending limb it resembles that of the spiral tubule. The 

 epithelium in the irregular or zigzag tubule is angular and markedly 



--"Artery of 

 capsule. 



Arched collect- - 

 ing tubule. 

 . Straight col- 

 lecting tu- " 

 bule. 



Distal convo- - 

 luted tu- 

 bule. 



Malpighian 

 corpuscle. 

 Proximal con- t 

 voluted tu- C, 

 bule. 

 Loop of Henle. ( ~ 



Collecting 

 tubule. 



Arteria arcua- 

 ta. 



Large collect- - 

 ing tubule. 



Glomer- 

 ulus. 



arcuata. 



Papillary duct. 



m 



FIG. 240. Diagrammatic scheme of uriniferous tubules and blood-vessels of kidney ; 

 drawn in part from the descriptions of Golubew (Bohni and Davidoff). 



striated ; in the second convoluted tube it is like that in the first ; in 

 the junctional tubes, flat and cubical ; in the straight or collecting 

 tubes, clear cubical and columnar; and in the ducts of Bellini, 

 clear columnar. 



The following table, from Schafer's Essentials of Histology, 

 exhibits the differences in the epithelium of the tubules in a manner 

 very useful for reference : 



