THE DEVELOPMENT OF THE UROGENITAL SYSTEM. 



365 



vessels enter and leave. Thus a double layer of epithelium comes to surround 

 the glomerulus, the space between the two layers being the extreme distal part 

 of the lumen of a renal tubule. The inner layer is closely applied to the surface 



Anlagen of 

 convoluted 

 renal tubules 



Renal pelvis 



Capsule 



Anlage of 



convoluted renal tubule 



Ampulla of 

 straight renal tubule 



FIG. 315. Sagittal section of the anlage of the left kidney in a rabbit embryo of 15 days. Schreiner. 

 The straight renal tubules (sections of which are shown) are embedded in the metanephric blastema. 



Condensations of the latter form the anlagen of the convoluted renal tubules. At the left 



of the figure several mesonephric tubules are shown. 



Amp. 



Con. r. t. 



Met. bl. 



Con. r. t. 



FIG. 316. From a section of the kidney of a human foetus of 7 months. Schreiner. 



Amp., Ampulla of a straight renal tubule; Con. r. t., anlagen of convoluted renal tubules, above and 



between which are two ampullae (compare Fig. 317); met. bl., metanephric blastema. 



of the glomerulus and even dips down into the latter between the tufts. The 

 outer layer forms Bowman's capsule, the flat epithelium of which passes over 

 into the cuboidal epithelium of the "neck" of the tubule, and this in turn is 



