FIGURE 20 



20 Transverse section of upper abdominal region of a 17 mm. cat embryo, show- 

 ing developing components of ascending Imnbar lymphatic trunks and of mesen- 

 teric sac in relation to embryonic veins in the root of the dorsal mesentery and their 

 relation to the cardinal collateral venous channels (series 258, slide XXIII, section 

 ■■J4j, X 75. 



1 Sympathetic nerve. 



7 Aorta. 



51 Mesenteric Ivmphatics. 



58 Ureters. 



61 Iliac vessels. 



62 End gut. 



63 Ventral divi.sion of clojira (urinary bladder). 



64 Wolffian ducts. 



66 Umbilical arteries. 



67 Right post cardinal vein. 



68 Left postcardinul vein. 



74 Cardinal collateral veins. 



75 Ascending hunh.ir Ivinphatic trunks. 



