Nonparenchymal liver cells and granulomas during lamprey biliary atresia

Abstract

Transmission (thin sections and freeze-fracture replicas) and scanning electron microscopy were used to describe the nonparenchymal liver cells during the seven (1-7) stages of metamorphosis in the sea lamprey, Petromyzon marinus L., when bile ducts and canaliculi degenerate. The biliary atresia is accompanied by an increased diameter of fenestrae in the endothelium, an active phagocytosis by Kupffer cells in the sinusoids, and large lipid inclusions in perisinusoidal lipocytes (fat-storing or Ito cells). Plasma-like cells and foci of nonparenchymal cells (granulomas) are present in the liver interstitium during at least four stages of metamorphosis. The fenestrae in the sinusoidal wall are wider (up to 2.8-micron diameter) than normally reported for vertebrate livers but are likely a reflection of the morphogenetic and physiological events and consequences of the biliary atresia. Kupffer cells are involved in an extensive erythrophagocytosis, the storage of iron, and perhaps the incorporation of cellular components from hepatocytes. Lipocytes are the vitamin A-storing cells of the transforming liver and may be responsible for some perisinusoidal fibrosis. Granulomas are present during stages 3-6 and are focal areas where mononuclear leukocytes (lymphocytes and plasmalike cells), macrophages, and neutrophils have infiltrated the hepatic parenchyma. The function of the granulomas is not known; but their presence may be related to the porous nature of the sinusoidal wall, the tissue degeneration, and/or the physiological change (e.g., bile stasis) during biliary atresia.

Pronephric regression during larval life in the sea lamprey, Petromyzon marinus L.

“…In the lamprey, the majority of granulocytes are neutrophils (for review see Potter et al 1982) and it is possible they are involved in phagocytosis. The macrophages observed in the pronephric region have a similar morphology to those observed in the lamprey liver as it undergoes biliary atresia (Youson et al 1987b) and their presence is consistent with the view that pronephric degeneration is an apoptotic process. However, it is in contrast to the regression of the larval lamprey opisthonephros (Ooi and Youson 1979) and the regressing human mesonephros (DeMartino et al 1977) where phagocytic cells were uncommon or absent between the degenerating tubules.…”

Cholangiocyte apoptosis is an early event during induced metamorphosis in the sea lamprey, Petromyzon marinus L

“…A unique internal change associated with metamorphosis in the lamprey is involution of the biliary system [7]. Morphologic changes in the livers of sea lampreys undergoing spontaneous metamorphosis have been characterized by light and electron microscopy in a series of papers by Youson and colleagues [19][20][21][22][23][24]. Specific to changes in the morphology of the bile ducts, Sidon and Youson [19] reported that the earliest evidence of bile duct degeneration was not observed until stage 2 of spontaneous metamorphosis when "the basal lamina takes on a folded appearance at certain positions around the ducts."…”

Vitamin A distribution and content in tissues of the lamprey, Lampetra japonica

“…The distribution, localization, and fine structure of the stellate cells in the liver of adult lamprey were studied by Youson et al (1985Youson et al ( , 1987, Peek et al (1979), and Wake et al (1987). The stellate cells in the lamprey liver store vitamin A as lipid droplets in their cytoplasm, but differ in some of their properties from their counterpart in the mammalian liver.…”

“…The stellate cells in the lamprey liver store vitamin A as lipid droplets in their cytoplasm, but differ in some of their properties from their counterpart in the mammalian liver. These cells are responsible for periductal fibrosis during biliary atresia in the lamprey (Yamamoto et al, 1986;Youson et al, 1987).…”