176 



THE ENTODERMAL CANAL AND THE BODY CAVITIES 



Referring to Fig. 88, it will be seen that the hver anlage lies between the 

 vitelline veins and is in close proximity to them laterally. The veins send anas- 

 tomosing branches into the ventral mesentery. The trabeculae of the expanding 

 liver grow between and about these venous plexuses, and the plexuses in turn 



Fig. 184. — The trabeculae and sinusoids of the liver in section (after Minot). X 300. Tr., Trabeculse 



of liver cells; Si., sinusoids. 



make their way between and around the liver cords (Fig. 183). The vitelline 

 veins on their way to the heart are thus surrounded by the liver and largely sub- 

 divided into a network of vessels termed sinusoids. The endothehum of the sinu- 

 soids is closely applied to the cords of liver cells, which, in the early stages, contain 



A B 



Gall bladder 



Gall 

 bladder 



Cystic duct 

 Ductus ckoledochus 



Ventral pancreas 



Dorsal 

 pancreas 



Cystic duct 



Hepatic duct 



Ductus ckoledochus 



Ventral pancreas 



-Duodenum 



Duct of dorsaU 



pancreas 



Head of dorsal pancreas 



Duodenum 



Tail of 

 dorsal 

 pancreas 



o 



Fig. 185. — Reconstructions showing the development of the hepatic diverticulum and pancreatic anlages. 

 A, 7.5 mm. human embryo (after Thyng), X 50; B, 10 mm. human embryo, X H. 



no bile capillaries (Fig. 184). The transformation of the vitelline veins into the 

 portal vein and the relations of the umbilical veins to the liver will be treated in 

 Chapter IX. 



The glandular portion of the liver grows rapidly, and, in embryos of 7 to 8 

 mm., is connected with the primitive hepatic diverticulum only by a single cord 



