THE METANEPHROS 



201 



mesonephric duct. The secretory tubules and the capsules of the renal 

 corpuscles are differentiated from the isolated caudal end of the nephro- 

 genic cord and thus have a similiar origin as the mesonephric tubules. 



Mesonephric duct 



Hind-gut 



^ lk ^ 



Outer zone of nephrogenic cord] 

 Inner zone of nephrogenic cord 

 'this of kidney 



Bladder 



Cloacat membrane 



FIG. 209. Reconstruction of the anlages of the metanepbros in a human embryo of about 9 



mm. (after Schreiner). 



D 



Cranial pole tubule 



Cranial 

 pole tubule 



Caudal 

 pole tubule 



Ureter 



Cranial 

 pole tubule 



/Central 

 tubule 



Pelvis 



Caudal 

 pole tubule 



Ureter^ 



Ventral central 

 tubule 



Secondary 



collecting 



tubules 



Tertiary collecting 

 tubule 



FIG. 210. Diagrams showing the development of the primitive pelvis, calyces and collecting 

 tubules of the metanephros (based on reconstructions by Schreiner and Felix}. 



In embryos of about 5 mm. the mesonpheric duct makes a sharp bend 

 just before it joins the cloaca, and it is at the angle of this bend that the 

 ureteric evagination appears, dorsal and somewhat median in position 

 (Fig. 216, B, C). The bud grows at first dorsally, then cranially. Its 



