ductopenia
This refers to the eventual actual loss of the bile ducts due to a progressive cycle of bile duct damage. There seems a combined action of our immune system as well as the toxic effects of bile acids that accumulate in the disease process.
The cells that form the lining of the bile ducts are called Biliary Epithelial Cells (BEC). It is the group of BEC that are the specific target for damage as the disease progresses.