DEVELOPMENT OF LIVER AND PANCREAS 



251 



some distance. Anteriorly there is quite a distinct furrow between 

 the Hver and the pancreas. A model of this stage (fig. 24) shows 

 the outpouchings of the pancreas and of the gall-bladder and 

 liver anteriorly. Posteriorly there is no sharp demarcation of 

 the pancreas from the yolk-mass and gut. A model of the 

 lumina of the pancreatic evaginations and of the gall-bladder 

 and hepatic ducts makes the position of the different parts with 

 reference to the antero-posterior plane more clear (fig. 25). At 

 this stage the pancreatic anlagen are caudal to the gall-bladder 

 which is directly anterior to the right pancreatic evagination. 



Fig. 24 Lateral view of a reconstruction of the pancreatic anlagen of a 9 

 mm. embryo. X 40. D.pan., dorsal pancreas; Li., liver; St., stomach; V.pan., 

 ventral pancreas; Y, yolk-gut. 



Fig. 25 Lateral view of a reconstruction of the lumina of the gut and pan- 

 creatic anlagen. X 40. G.b., gall-bladder; other abbreviations, as in figure 24. 



The pancreatic evaginations extend farther ventrally than do 

 the hepatic ducts and the gall-bladder. 



The right and left pancreatic anlagen are separated anteriorly' 

 by a slight ventral furrow. Caudally the two evaginations are 

 apparently fused as the area between them is bulged ventrally. 

 The evidence of a division into two evaginations is much more 

 clear in a view of the model of the lumina of the pancreatic 

 anlagen (fig. 25). This is also brought out clearly by the figure 

 of a section taken about 80/^ caudal to the gall-bladder (fig. 26). 

 In this figure one sees the two very definite evaginations, and 



