324 



THE DEVELOPMENT OF THE CHICK 



has correspondingly in the adult three separate ducts opening 

 into the duodenum. (Two pancreatic ducts is the rule in Gallus, 

 according to Gadow in Bronn's Thierreich.) Of the three pan- 

 creatic diverticula, the dorsal one arises first (about 72 hours) 

 then the right ventral slightly earlier than the left ventral 

 (about 96 hours). The two latter arise from the common 



Ao. 



V.c.fl 



Mist. 





!»« 





CdV.f. 





^J^^^l^.Jj. 





'iS ^. o'a"'*'?. 



,; 6 ;. 



.«„» 



Coel: 







0(1 



V- 



^' 



".o.md 



&^ 





^ /^ f| -^-^ — V t' * "- ^^^/. 









!> * t'- 1 " •■ 



.■'a .a »-' i - 



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A V 



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l>.hej}. 2. 



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Fig. 188. — Transverse section through the duodenum and hepato- 

 pancreatic ducts of a chick embryo of 5 days. (After Choronschitzky.) 

 Ao., Aorta, cav. F., Caval fold. Coel., Coelome. D. hep. 2, 2 a, 

 2 b, Posterior hepatic diverticulum and branches of same. Du., Du- 

 odenum. Li., Substance of liver. M'st., Dorsal mes-ntery. Pa. d., 

 Dorsal pancreas. Pa. v. d.. Right ventral pancreas. Pa. v. s., Left 

 ventral pancreas. Spl., Spleen. V. c. p., Postcardinal vein. V. h., 

 Vena lienalis. V. o. m. d., Right omphalomesenteric vein. V. o. m. s., 

 Left omphalomesenteric vein. 



hepatic diverticulum near its junction with the duodenum (Fig. 

 188). The differentiation of the three parts is essentially similar, 

 and proceeds naturally in the order of their origin. Solid buds 

 arise from the ends of the diverticula, and these branch repeatedly 

 in the surrounding mesenchyme, but do not anastomose; the 



