i:^2 THE STUDY OF SIX AND TEN MILLIMETER PIG EMBRYOS 



Sl-iii il inid 



Spinal I iiiiji II 



Spill il III I 



Post, cardinal in 

 Mesonephi i s 



Pleural cavil \ 

 Upper limb bud 



\ — \ lochord 



Dorsal aorta 

 Esophagus 



Wf Bifurcation of trachea 



Inferior vena cava 



Fig. 136. — Transverse section through the liver and upper limb buds of a 10 mm. pig embr>'o at the level 

 of the bifurcation of the trachea. X 22.5. 



R. Inn 



Esophai^ii 

 Lesser peritoneal sai 



Inferior vena cnui 



ganglion 

 iidinal vein 



[esonephric tubide 



Peritoneal cavity 

 Dorsal lobe of liver 



— 'Sinusoids of liver 



Ductus venostis 



Fig. 137. — Dorsal half of a transverse section through the lung buds cranial to the stomach in a 10 mm. 



pig embryo. X 22.5. 



Section through Lung Buds Cranial to Stomach (Fig. 137). — The lungs are sec- 

 tioned through their caudal ends and the esophagus is just beginning to dilate into the 



