Distribution of the nerves of the hepatic vein with special reference to innervation of its sphincter: whole mount immunohistological observation in Suncus murinus.

Abstract

Background: Morphological and functional studies of the human cavo-hepatic junction have been widely reported. The unique spiral structure of the wall of the canine hepatic venous system, which is formed by smooth muscle bundles, and the ultrastructure of the hepatic venous sphincter of animals, especially dogs, have also received a great deal attention. However, studies on the innervation of the hepatic vein in this structure have rarely been reported.

Materials and methods: In this study, experimental animals Suncus murinus (n = 9) were subjected to pressurized perfusion and fixation. The liver was removed, and the liver parenchyma was carefully removed, leaving only the intrahepatic vasculature. Whole-mount immunohistochemical staining with a neurofilament protein antibody was performed to identify the nerves of the hepatic vein.

Results: Abundant NFP-positive nerves were present near the hepatic venous outflow tract, which were connected to the IHC nerves. However, no NFP-positive nerve fibers were found in the deep hepatic, sublobular, or collecting veins.

Conclusions: Our studies on Suncus murinus, have shown that the nerve distribution of the hepatic vein is quite different from that of the hepatic artery, portal vein, and bile duct system entering and exiting the liver portal. The nerve distribution of the latter can extend to deeper layers of the intrahepatic artery, portal vein, and intrahepatic bile duct system. Innervation of the hepatic vein was mainly observed at the entrance of the hepatic vein into the IVC. These nerves may innervate the hepatic sphincter and control the outflow of hepatic veins.