Ultrastructure of cholinergic innervation in the cirrhotic liver in guinea pigs. Neurohistochemical and ultrastructural study.

Hepatic cirrhosis was induced in guinea pigs by ligation of the common bile duct and innervation of the liver was studied by fluorescence histochemistry (glyoxylic acid method), acetylcholinesterase (AChE) neurohistochemistry (modified Karnovsky and Roots method), and transmission electron microscopy. In control animals the adrenergic terminals showed connections with endothelial cells, hepatocytes and fat-storing cells, but no cholinergic terminals were evident. Cirrhosis was present 6 weeks after the bile duct ligation and marked fibrosis, accompanied by bile duct proliferation, was evident in the portal areas. Numerous AChE-positive nerve fibers traversed the collagenous bundles in the fibrotic areas, and cholinergic terminals formed close contacts with fibroblasts. Each axon terminal was found to contain numerous small coreless vesicles and AChE-reaction products were confirmed in the space between a nerve terminal and a fibroblast. In contrast, fluorescence adrenergic nerve fibers and their terminals remained unchanged. This study demonstrates that parasympathetic cholinergic innervation participates in some stages in the development of hepatic cirrhosis.