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.

Temperature and gender influences on the hepatic stroma (and associated pancreatic acini) of Nile tilapia,Oreochromis niloticus (Teleostei, Cichlidae): A stereological analysis by light microscopy

“…There were modifications in both the relative and total volumes, which implies that there was an adaptative proliferation (ramification) and/or hypertrophy (elongation or dilation) of the biliary ducts, in both genders, induced by acclimation to the higher temperature. To our knowledge, this is a new finding for fish (or even for vertebrate) liver, as bile duct hyperplasia and/or hypertrophy are often referred to in fishes, but in connection with disease status, from parasitoses (Eng and Youson, 1992) to neoplasms (Boorman et al, 1997). We are compelled to hypothesize that our results reflect, at least partially, an adaptative response to the increased metabolic demand and consequent eventual increase in bile traffic, and also that some stimuli (e.g., heat-shock proteins, chaperones) target the biliary epithelial cells, inducing them to proliferate and/or enlarge.…”

Comparative morphology of the gallbladder and biliary tract in vertebrates: Variation in structure, homology in function and gallstones

“…A large spherical-to-ovoid nucleus is found in the basal portion and numerous mucus granules in the apical region of each bile duct cell. An occasional cilium was observed at the apical surface of the intrahepatic bile duct cells (Eng and Youson, 1992). Interesting studies done by Sorensen and colleagues (Li et al, 1995) indicate that lampreys appear to find their spawning stream by following the scent of a unique bile salt, petromyzonol sulfate, only made when they are larvae.…”

“…The nematode Truttaedacnitis stelmiodes infects the bile ducts of the larval brook lamprey (Lampetra lamottenii). The intrahepatic bile ducts are dilated and the apical cell surfaces ranged from those with appearances similar to uninfected fish to surfaces with shortened microvilli, dome-shaped apices, flattened apices, and many with cytoplasmic extrusions (Eng and Youson, 1992).…”