DEVELOPMENT OF THE VEINS 



225 



The lower communication between the vitelline veins takes the form of a 

 complete longitudinal fusion of the two vessels, at least for some distance. This 

 fused part receives veins from the intestine and stomach, and becomes the 



A/ an/if 



right horn 

 sinus veno.tH: 





right umbilical vein 



distal venous rii 

 right vilt 



FIG. 279. THE VEINS OP THE LIVER OP A HUMAN EMBRYO OF 6'9 MM. (After Ingalls.) 



"Hint ve; 



left litelline vein 



anterior detached portions 

 of umbilical vein* 



rente revehentes 



stomach 



venai adeehentes 

 pancreas 



bile-duct 



obliterated portions 

 of venous rings 



right umbilical iv/// 



ductus venosus 

 (Arantii) 



lifer 



left umbilical vein 



vitelline reins 



duodenum 



FIG. 280. THE LIVER, AND THE VEINS IN CONNECTION WITH IT, OP A HUMAN EMBRYO, TWENTY-FOUR 



OR TWENTY-FIVE DAYS OLD, AS SEEN FROM THE VENTRAL SURFACE. (After His.) (Copied from 



Milnes Marshall's Embryology.) 



commencement of the portal vein. At a later date the vitelline veins distal to this 

 point are obliterated, and the new veins in the mesentery become the tributaries 

 of the portal vein of the adult. 



VOL. I. Q 



