Alterations of the myoid pericanalicular layer in liver. A light microscopical pilot study of human autopsy material.

Previous histochemical studies demonstrated a myoid layer along biliary pathways. This report describes alterations of the pericanalicular layer in various lesions. Carnoy- or methacarn-fixed sections of livers from 200 autopsies were treated with the tannic acid-phosphomolybdic acid-dye method for myosins. In other series, methods for myosins were combined with the picro-Sirius Red F3BA stain or the Prussian Blue reaction. In normal liver, bile canaliculi were lined by a narrow myoid layer. In other cases, eg, hepatic cirrhosis, the pericanalicular layer showed slight to moderate thickening. In cases with obstruction or atresia of bile ducts, the dilated canaliculi were surrounded by a prominent myoid layer. These observations support theories that the pericanalicular layer is contractile and promotes bile flow under positive pressure.