Morphology of the bile ducts of the brook lamprey, Lampetra lamottenii (Le Sueur) before and during infection with the nematode, Truttaedacnitis stelmioides (Vessichelli, 1910) (Nematoda: Cucullanidae).

Abstract

Routine light microscopy and transmission and scanning electron microscopy were used to describe and compare the biliary tree of larval Lampetra lamottenii before and during infestation of the bile ducts with the nematode, Truttaedacnitis stelmioides. The most prominent changes to the biliary tree following infection by the parasite are the dilation of the bile ducts, alterations to their epithelial cells, and an increase in periductal fibrous tissue. In recently infected animals, the simple epithelium of dilated bile ducts often contains many mitotic figures. In long-term infestations, the epithelium is stratified or pseudostratified. Changes to the fine structure of the biliary epithelial cells include increase and/or dilation of the RER and SER, and increases in microfilaments, intermediate filaments, and microtubules. The abundance of dense bodies may reflect enhance reabsorption of biliary constituents, and their accumulation may ultimately result in cytolysis. There are increased mucous granules in the apical cytoplasm of biliary epithelial cells and an abundance of mucinous material within the bile duct lumen, and the basal lamina appears thickened. The changes to the liver of L. lamottenii following infection are discussed and compared to those reported in small mammals following bile duct ligation, in patients with extrahepatic biliary obstruction, and in parasitic infection of the biliary tree.