96 THE STUDY OF SIX AND TEN MILLIMETER PIG EMBRYOS 



near the cardiac end of the stomach, and project into the pleural ccelom. The 

 esophagus is short and widens dorso-ventrally to form the stomach. The long 

 axis of the stomach is nearly straight, but its entodermal walls are flatteaed 

 together and it has revolved on its long axis so that its dorsal border lies to the 

 left, its ventral border to the right, as seen in transverse section (Fig. 111). 



Caudal to the pyloric end of the stomach, and to its right, is given off from 

 the duodenum the hepatic diverticulum. Its opening into the gut is seen in the 

 ventral dissection (Fig. 97). The hepatic diverticulum is a_sac ofelongated oval 

 form from which the hver and part of the pancreas take origin, a.nd which later 

 gives rise to the gall bladder, cystic duct, and common bile duct. It is coimected 

 by several cords of cells with the trabeculae of the hver. 



The liver is divided incompletely into four lobes, a small dorsal and a large 

 ventral lobe on each side (Figs. 95 and 112). The lobation does not show in a 



Lateral lingual anlage- 



L ■ .- . . BrdnfhJal arch I 



\ 



^sTZ — 



Tuberculum impar ■ ^^-. ._ — — Brjnchial arch II 



Epiglottis '^ -^^^—Jr-^^^ ~T-^ Br.nn-lnal arch III 



Sraiicliial arch IV 



Arytenoid ridge 



Glollis 



Fig. 98. — Dissection of the tongue and branchial arches of a 7 mm. pig embryo, seen in dorsal \-iew. X IS. 



median sagittal section. The pancreas is represented by two outgrowths. The 

 ventral pancreas originates from the hepatic diverticulum near its attachment 

 to the duodenum (Fig. 96). It^grawsto the right of the duodenum and-veirtrat 

 to the portal vein. Tha dorsal pancreas takes origin from the dorsal side of the 

 duodenum xaudal tojjie hepatic diverticulum and grows dorsally into the sub- 

 sta.nce of the gastric mesentery (Figs. 105 and 113). ItTs larger than the ventral 

 pancreas, and its posterior lobules grow to the right and dorsal to the portal vein 

 and in later stages anastomose with the lobules of the ventral pancreas. 



The iniestme of both fore-gut and hind-gut has elongated and curves \^en- 

 trally into the short umbilical cord where the yolk stalk has narrowed at its point 

 of attachment to the gut (Fig. 96). As the intestinal tube grows ventrad, the 

 layers of splanchnic mesoderm which attach it to the dorsal body wall grow at an 

 equal rate and persist as the mesentery. 



