THE STUDY OF SIX AND TEN MILLIMETER PIG EMBRYOS 



the left side and is attached dorsally by the greater amentum, ventrally to the liver by the 

 lesser amentum. The right dorsal lobe of the liver is attached dorsally to the right of the 

 great omentum. In the liver, ventral to this attachment, courses the inferior vena cava 

 and the attachment forms the plica vena cava. Between the attachments of the stomach 

 and liver, and to the right of the stomach, is the lesser peritoneal sac. In the liver, to the 

 left of the midplane is the ductus venosus, sectioned just at the point where it receives the 

 left umbilical vein and a branch from the portal vein. The ventral attachment of the liver 

 later becomes the falciform ligament. 



Spinal cord 



Notochord 

 Mesonephros 



Plica vena cava 



Inferior vena cava 



Lesser peritoneal sac 



Portal vein 



Hepatic diverticulum 

 (Dl and gall bladder) 



R. umbilical vein 



Sympathetic ramus 

 Dorsal aorta 

 Dorsal mesogastrium 



Mesonephric duct 

 Stomach 



Ventral lobe of liver 



L. umbilical vein 



FIG. 139. 



Transverse section through the hepatic diverticulum of a 10 mm. pig embryo. 



X 22.5. 



Section through the Hepatic Diverticulum (Fig. 139)1 The section passes through the 

 pyloric end of the stomach and duodenum, near the attachment of the hepatic diverticu- 

 lum. The greater omentum of the stomach is larger than in the previous section and to its 

 right, in the plica venae cavae, lies the inferior vena cava. Ventral to the inferior vena cava 

 is a section of the portal vein. The ventral and dorsal lobes of the liver are now separate, 

 and in the right ventral lobe is embedded the saccular end of the hepatic diverticulum which 

 forms the gall bladder. To the right of the stomach, the diverticulum is sectioned again 

 just as it enters the duodenum. Ventrally, the left umbilical vein is entering the left ventral 

 lobe of the liver. It is much larger than the right vein, which still courses in the body wall. 

 On the left side of the embryo the spinal nerve shows in addition to its dorsal and ventral 

 rami a sympathetic ramus, the fibers of which pass to a cluster of ganglion cells located 

 dorso-lateral to the aorta. These cells form one of a pair of sympathetic ganglia and are 

 derived from a spinal ganglion. 



