Mechanism of benign biliary stricture: A morphological and immunohistochemical study

Abstract

To explore the mechanism of benign biliary stricture. A model of trauma of bile duct was established in 28 dogs. The anastomosed tissues were resected and examined by light and electron microscopes on day 3, in wk 1, 3 and mo 3, 6 after operation. CD68, TGF-beta1 and alpha-SMA were examined by immunohistochemical staining, respectively. The mucosal epithelium of the bile duct was slowly recovered, chronic inflammation lasted for a long time, fibroblasts proliferated actively, extracellular matrix was over-deposited. Myofibroblasts functioned actively and lasted through the whole process. The expression of macrophages in lamina propria under mucosa, TGF-beta1 in granulation tissue, fibroblasts and endothelial cells of blood vessels, alpha-SMA in myofibroblasts were rather strong from the 1st wk to the 6th mo after operation. The type of healing occurring in bile duct belongs to overhealing. Myofibroblasts are the main cause for scar contracture and stricture of bile duct. High expressions of CD68, TGF-beta1 and alpha-SMA are closely related to the active proliferation of fibroblasts, extracellular matrix over-deposition and scar contracture of bile duct.