THE UROGENITAL SYSTEM 



431 



SPINAL CORD^ 



SPINAL 

 GANGLION _/.. J 



1 MESONEPHRIC TUBULES 



NEPHROSTOME 



GLOMERULUS 

 POSTCARDINAL VEIN 



PERITONEUM '\v PR'MiTIVE DUCT 



MESENTERY PRONEPHRIC TUBULES 



Fig. 355.— StcreLiferani ot the developing pronephros and mesonephros. (After Kingsley 



modified.) 



post, cardinal 

 vein 



nephrostome 



glomus 



somite 



dorsal aorta 



D 



nephrostome 

 ' glomerulus 



Fig. 356. — Drawings to show structure of nephric tubules. A. Pronephric tubule 

 from section through 12th somite of a i6-somite chick embryo. (After Lillie.) B. 

 Diagram of functional pronephric tubule. (After Wiedersheim.) C. Primitive meso- 

 nephric tubule with rudimentary nephrostome, from section through 17th somite of 

 30-somite chick embrj'o. D. Schematic diagram of functional mesonephric tubule of 

 the primitive type which retains the nephrostome. (After Wiedersheim.) (From 

 Patten's "Embryology of the Chick.") 



