Abstract
The innervation of the human liver was investigated by the electron microscopy. In the portal area, unmyelinated nerve bundles were found close to the fibroblasts with collagen fiber around the portal vein, bile duct, hepatic artery, and lymph vessel. Moreover, the Schwann cells with many axons were found in the portal area.
In the mid-zonal area of the lobule, unmyelinated nerve bundles were found running between the Ito cell and the hepatocyte, and also between hepatocytes. The varicosities appeared to face the Ito cell or hepatocyte across a synaptic cleft.
Moreover, the varicosities showed in direct contact with hepatocytes. The collagen bundles were found close to the Ito cells or hepatocytes.
In the centrolobular area, the longitudinal axons were found between hepatocytes near the central vein. Moreover, small unmyelinated nerve ending faced the myofibroblast across a synaptic cleft, and the endothelial cell by way of the basal lamina.
In addition, the varicosities of the nerve ending in the human liver contain many small agranular and granular vesicles, large dense core vesicles, and also many cytoskeletons. It is suggested that the adrenergic innervation exists in the human liver. Moreover, it is suggested that nerves in the human liver have a close relation with intrahepatic vessels or cells, and especially contribute to the contraction of the fibroblast, Ito cell, or myofibroblast around the vessels in the portal area, sinusoid, or central vein.
