The Anatomy of the Human Peritoneum and Abdominal Cavity / Considered from the Standpoint of Development and Comparative Anatomy

by George S. Huntington

Fig. 270.—Veins of pigeon, Columba livia. (Modified from Parker and Haswell.) The renal-portal vein of the right side is supposed to be dissected to show its passage through the right kidney.

4. Bird.—The characteristic change in the venous system of the bird, as compared with that of the amphibian and reptile, is found in the nearly complete abolition of the renal portal system. The caudal vein bifurcates, sending on each side a large trunk, which receives the pelvic (int. iliac) veins, to the kidney (renal afferent portal vein), but only a few small branches enter the substance of the gland (Fig. 270, afferent renal V). The main vessel continues cephalad through the kidney and, after receiving the vein from the posterior extremity (femoral), unites as common iliac vein with the vessel of the opposite side to form the postcava. This vessel traverses the liver, receiving the hepatic afferent veins of the portal system. The portal vein is formed by tributaries from the intestinal canal, pancreas and spleen, and is also joined by a large coccygeo-mesenteric vein, which is given off at the point of bifurcation of the caudal vein and receives tributaries from the lower part of the alimentary canal. The abdominal vein of amphibians and reptiles is represented probably by the epigastric vein, which returns the blood from the omental mass of fat to the hepatic veins.

Compared with the mammal on the one hand, and with the lower types on the other, the venous circulation of the bird illustrates the following points:

1. Extensive reduction of the renal portal system and direct formation of postcava by the iliac veins, foreshadowing the condition found in the mammal.

2. Complete separation of the portal and systemic venous circulation in the adult. Disappearance of the ventral abdominal vein as a vessel of the body wall.

5. Human Fœtus at Term.—The student is recommended to examine, by dissection and injection, the venous system of a fœtus at term, noting the following facts:

Fig. 271.—Human fœtus at term. Corrosion preparation of heart and vascular system. (Columbia University Museum, No. 1858.)

1. Course of umbilical vein in ventral abdominal wall and along free edge of falciform ligament to liver ([Fig. 241]), corresponding to the position of the amphibian and reptilian abdominal vein ([Figs. 264] and [275]).