THE URINOGENITAL SYSTEM 



385 



of the mesonephros are formed (Fig. 219). During its growth 

 forward a series of small diverticula arise from its wall and extend 

 dorsally (Fig. 223) ; these branch secondarily in a generally dichot- 



A&'t. 



FIG. 222. Transverse section through the metanephros, mesonephros, 

 gonads and neighboring structures of an 11-day male chick. 



a. A. S., Abdominal air-sac. Ao., Aorta. B. W., Body-wall. Coel., Coe- 

 lome. Giz., Gizzard. II., Ilium. M. D., Remains of degenerating Miillerian 

 duct. MVt., Mesentery. M't'n., Metanephros. Sp., Spine of neural arch, 

 tr. Pr., Transverse process of the neural arch. V. c. i., Vena cava inferior. 

 W. D., Wolffian duct. Other abbreviations as before. 



