nephrogenic tissue 



.:sk;ii: arched collecting duct 



_ampullo 



3rd generation nephron 

 ^first generation nephron 



-minor calyx 



2nd generation nephron 



V-'^X^^i ^^"-'^^i 



r^^^ 





Ist generation nephron 

 primary collecting duct 



-minor calyx 



Figure 10-6. Three diogrammatic stages in the development of successive generations of tubules in 

 the mammalian metanephros. (After Patten, 1946) 



arched collecting duct 



istal convoluted tubule 



Henle's loop 



glomerulus 

 Bowman's capsule 



B 



arched collecting duct 



distal convoluted tubule 



proximal convoluted tubule 

 glomerular blood vessel 



Bowman's capsule 

 juxtaglomerular region 



descending limb Henle's loop 

 ascending limb Henle's loop 



.straight collecting tubule 



thin segment of descending limb 



Figure 1 0-7. Three stages in the differentiation of a single metanephric tubule. (After Patten, 1 946) 



THE EXCRETORY SYSTEM • 295 



