. A laboratory manual and text-book of embryology. Embryology. 2y8 THE DEVELOPMENT OF THE VASCULAR SYSTEM The left vitelline vein is present except for the left limb of the cranial loop. A new vein, the superior mesenteric, develops in the mesentery of the intestinal loop and joins the left vitelline vein near the point of its dorsal middle connection with the right vitelline vein. Subsequently, with the atrophy of the yolk-sac the left vitelline vein degenerates caudal to its junction with the superior mesenteric vein. The persisting trunk from the superior mesenteric vein to the liver is the
. A laboratory manual and text-book of embryology. Embryology. 2y8 THE DEVELOPMENT OF THE VASCULAR SYSTEM The left vitelline vein is present except for the left limb of the cranial loop. A new vein, the superior mesenteric, develops in the mesentery of the intestinal loop and joins the left vitelline vein near the point of its dorsal middle connection with the right vitelline vein. Subsequently, with the atrophy of the yolk-sac the left vitelline vein degenerates caudal to its junction with the superior mesenteric vein. The persisting trunk from the superior mesenteric vein to the liver is the vena porta, and thus represents (i) a \(H VE PA V/C portion of the left vitelline vein in the left limb of the caudal loop; (2) the middle transverse anastomosis between the vitel- line veins; (3) the portion of the right vitelline vein which forms the right limb of the cranial loop. In the liver the portal vein through its cranial and ventral anastomosis between the vitel- line veins is connected with the left umbilical vein. As the right lobe of the liver grows, the course of the umbilical and portal blood through the intra- hepatic portion of the right vitelline vein becomes circui- tous, and a new direct channel to the sinus venosus is formed through the hepatic sinusoids. This is the ductus venosus Arantii, which is obliterated after birth and forms the ligamentum venosum of the post-natal Fig. 273.—A diagram showing the development of the portal vein (His in Marshall's Embryology). PA, pan- creas; TI, intestine; TS, stomach; VA, left umbilical vein; VA', right umbilical vein; VA", cranial detached portions of umbilical veins; VE, ductus venosus; VH, efferent hepatic vein derived from right vitelline; VL, afferent hepatic vein; VO, trunk of portal vein derived from left vitelline; VV, right vitelline vein; VV, on right side of figure, superior mesenteric vein; VV, VV", por- tions of right and left vitelline veins which atrophy; W, liver; WD, bile d
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectembryology, bookyear1
