DEVELOPMENT OF LIVER AND PANCREAS 249 



Gianelli ('99) described an ''intrahepatic pancreas" in Triton, 

 the tubules of which are in intimate relation with the liver- 

 tubules, and it is stated by him are continuous with them. 



Renter ('00) made mention also of the early appearance of 

 the dorsal and ventral pancreas. Both arise from the anterior 

 part of the midgut region (Anfangsdarm) from the yolk-cells. 

 The pancreas, as well as the liver, is found in the gastro-duodenal 

 loop as soon as this is formed, and both are at first to the right 

 and dorsal to the intestinal spiral. 



Choronshitzky ('00) described in Necturus and the frog two 

 lateral outpouchings from the early hepatic duct. These two 

 lateral outpouchings form the ventral ducts, later they unite 

 posterior (ventral) to the common duct. He described two ducts 

 in the adult urodeles. 



Gianelli ('02) described three distinct pancreatic anlagen in 

 Triton. The dorsal anlage develops first. The ventral anlagen 

 develop from the posterior end of the hepatic outpouching as 

 two masses of vitelline cells into which the lumen of the hepatic 

 evagination later extends. The right and left outpouchings 

 both fuse with the dorsal pancreas. The ventral pancreatic 

 duct formed from both pancreatic anlagen opens into the hepatic 

 duct. The left pancreas remains in intimate relation with the 

 liver. 



Braun ('06) described the early development of the pancreas 

 in Alytes obstetricans. He found a dorsal and two ventral 

 pancreatic anlagen, which are first to be recognized as swellings 

 of the yolk-gut wall and by the more numerous nuclei. The 

 ventral anlagen are caudal to the anlage of the hepatic duct. 

 The right ventral pancreas is somewhat more caudal than the 

 left, joins the dorsal pancreatic outpouching and later joins with 

 the left ventral pancreas. The dorsal outpouching looses its 

 connection with the yolk-gut soon after coming in contact with 

 the right ventral pancreas. The cells forming the pancreas are 

 at this time still undifferentiated yolk-cells. Differentiation of 

 the cells and glandular development take place at the same time. 

 The early ventral outpouchings develop into the pancreatic 

 ducts which unite just before opening into the gut to the right of 



