Ducts versus tissue. The biliary tree is a network of pipes running through the liver tissue. Liver disease can often be divided into those affecting the pipes versus those affecting the tissue (which is made up of liver cells). Diseases which primarily affect the liver cells (and not the pipes) are considered parenchymal.
Means tissue. The liver is composed of tissue, blood vessels, and a duct system sort of like storm drains. Junk from the body goes in blood to the liver thru arteries to capillaries& passes thru tissue where work is done.Cleaned blood goes thru veinules to veins & back to the body. The junk ends up in ducts and is dumped into the intestines. Parenchmal disease affects tissue, rather than the rest.