DIFFERENTIATION OF THE NEPHROGENIC TISSUE 



211 



proximal, convoluted 

 tubule 



Distal convoluted 



tubule 

 Renal corpuscle 



Connecting piece 



Ascending limb 

 of Henle's loop 



Descending limb 

 of Henle's loop 



Large collecting 

 tubule 



Arch of collecting tubule 



Arch of colkctinq 

 tubule ' 



Dista convoluted 



tubule 

 Stoerck's loop 



Proximal coni/olut- 

 tubuie 

 Connecting piece 

 Glomerulus 



Bowman's capsule 



Arch of collecting 

 tubule y 



Proximal convoluted 

 tubule 



Distal Convoluted, 

 tubule , 

 Connecting piece 



Glomerulus 



Bowman's capsule 

 Stoerck's loop 



Fig. 206. — Diagrams showing the differentiation of the various parts of the uriniferous tubules of 

 the metanephros (based on the reconstructions of Huber and Stoerck). A, from an adult human kid- 

 ney; B, C, from human embryos. 



its thin inner wall becoming the 

 uriniferous tubules of the adult 

 kidney have a definite and 

 peculiar structure and arrange- 

 ment (Fig. 207 A). Beginning 

 with a renal corpuscle, each 

 tubule forms a proximal con- 

 voluted portion, a U-shaped loop 

 (of Henle) with descending and 

 ascending limbs, a connecting 

 piece, which lies close to the 

 renal corpuscle, and a distal 

 convoluted portion continuous 

 with the collecting tubule. 

 These parts are derived from 

 the S-shaped anlage, which is 

 composed of a lower, middle and 



capsule (Bowman's) of a renal corpuscle. The 

 a- 



m- 



Fig. 207. — Diagram showing the relation of Bow- 

 man's capsule and the uriniferous tubules to the collecting 

 tubules of the metanephros (Huber). c, collecting tubules; 

 e, end branches of collecting tubules; m, renal corpuscles; 

 n, neck; pc, proximal convoluted tubule; pi, descending 

 limb of Henle's loop; al, ascending limb of Henle's loop; 

 dc, distal convoluted tubule; j, junctional tubule. 



