Intrahepatic bile ducts in biliary atresia--a possible factor determining the prognosis

Intrahepatic bile ducts were investigated by operative cholangiography in 6 patients with the correctable type of biliary atresia, by percutaneous transhepatic cholangiography in 5 patients with noncorrectable type and by electron microscopy in biopsied hepatic tissues in 17 patients. Intrahepatic bile ducts were pathologic even in the early stage of the disease and they were involved all the way from bile ductules to large main hepatic ducts. The correlation between the prognosis and the electron microscopic presence of lumenal obstruction suggests that the pathologic change of intrahepatic bile ducts is one of the main factors determining prognosis.

Photosensitivity in South Africa. V. A comparative study of the pathology of the ovine hepatogenous photosensitivity diseases, facial eczema and geeldikkop (Tribulosis ovis), with special reference to their pathogenesis

The subject of this study was the pathological and scanning electron microscopical changes in the biliary systems of sheep suffering from facial eczema or geeldikkop (Tribulosis ovis), or made photosensitive by ligation of the common bile duct. While an obliterative cholangitis is responsible for the retention of phylloerythrin in facial eczema, the occlusion of bile ducts with crystalloid material (microliths) appear to perform a similar function in geeldikkop. The similarities and differences between the 2 diseases are discussed in the light of their pathogenetic mechanisms.

Primary cultures of rat hepatocytes as a model system of canalicular development, biliary secretion, and intrahepatic cholestasis. I. Distribution of filipin-cholesterol complexes during de novo formation of bile canaliculi

Hepatocytes in primary monolayer culture reconstitute structural intact bile canaliculi sealed by tight junctions. Using filipin as a cytochemical marker for cholesterol-like membrane components in conjunction with the techniques of freeze fracture and thin sectioning, we have studied the distribution of cholesterol during the development of the biliary pole of cultured hepatocytes. It was found that the development of bile canaliculi is characterized in its very early stage by huge accumulations of filipin-cholesterol complexes located at distinct domains of the contiguous membrane. They were surrounded by junction formation zones almost devoid of these complexes, in which the alignment of intramembranous particles takes place. Maturation of the bile canaliculi was accompanied by dispersion of cholesterol within the canalicular membrane and its removal by segregation of cholesterol-rich membrane whorls and vesicles into the lumen. Finally, the luminal membranes, and particularly the areas studied with microvilli, contained only very few filipin-cholesterol complexes. In some cases, these seemed to be still arranged in small clusters. These alterations suggest a crucial role of cholesterol-rich membrane domains during initiation of a biliary polarity. On the other hand, cholesterol-poor (thus probably more fluid) areas might be required for the assembly of tight junctions, and appear to constitute the secretory active apical membrane present in the mature bile canaliculus.

Primary cultures of rat hepatocytes as a model system of canalicular development, biliary secretion, and intrahepatic cholestasis. II. Taurolithocholate-induced alterations of canalicular morphology and of the distribution of filipin-cholesterol complexes

Hepatocytes in primary monolayer culture treated with taurolithocholate showed distinct ultrastructural changes localized primarily to the bile canalicular membrane. These alterations comprised disturbance and proliferation of tight junctions, dilatation of the canaliculi, loss of microvilli, thickening of the pericanalicular ectoplasm, and bizarre lamellar transformations of canaliculi. In freeze-fracture replicas the lamellae projecting into the canalicular lumen were found to be devoid of intramembranous particles. Localization by the use of filipin of cholesterol in plasma membranes of taurolithocholate affected hepatocytes revealed an extensive accumulation of cholesterol in membranes of dilated canaliculi, and also in outpouchings of the contiguous membrane in the ultimate vicinity. Furthermore, a pronounced segregation of cholesterol-rich membrane material into the lumen of dilated canaliculi and into enlargements of the intercellular space could be observed in thin sections. In contrast, a total absence of cholesterol was noted in the lamellar projections of the bizarre transformed canaliculi. The reliability of these findings and their consequences for the mechanism of taurolithocholate-induced cholestasis are discussed and it is suggested that the incorporation of cholesterol into the canalicular membrane reflects only one aspect of the cholestatic effect of taurolithocholate. An additional aspect seems to comprise the dislocation of membrane bound proteins and perhaps other membrane components. This is probably caused by independent mechanisms.

Ultrastructural study of cholestasis induced by longterm treatment with estradiol valerate. I. Tight junctional analysis and tracer experiments

Over a period of 20 weeks estradiol valerate (1.5 mg/kg body weight/week) was administered subcutaneously to male Wistar rats from which the livers were examined at four week intervals employing a freeze-fracture technique and colloidal lanthanum tracer studies. In connection with intrahepatic cholestasis, distinct alterations in the tight junctions were observed, consisting of disorganization, rarification and proliferation. Disruption of the tight junctions was not seen and colloidal lanthanum did not penetrate into the bile canalicular lumen. Holding the view that the term "leakiness" of tight junctions should be defined with reference to the tracer employed, we conclude that in the liver one tight junctional strand is sufficient to prevent the escape of larger bile constituents such as bile acids and that a back diffusion of bile acids over the tight junctional barrier does not play a role in the pathogenesis of the estrogen-induced cholestasis. Interruptions of tight junctions, as described by other authors, are interpreted as a secondary mechanical effect. On the other hand, we consider an increased permeability of the tight junctions to water and small solute molecules as probable; possibly this increased permeability is brought about by alterations in the microfilaments. A model for the pathogenesis of the estrogen-induced intrahepatic cholestasis is proposed.

Electron microscopic observations on single cilia in the intrahepatic biliary ducts in some birds

The intrahepatic biliary passage in five species of birds was investigated with the transmission electron microscope. The avian liver was characterized by a frequent occurrence of intralobular bile ductules and canaliculo-ductular junctions in the parenchyma. It was further characterized by solitary bile ductular epithelial cells intercalated among hepatocytes surrounding bile canaliculi. The present study first revealed that avian bile ductular epithelial cells possess a long single cilium. Its basal body (distal centriole) was connected to a basal foot and slender rootlet and accompanied by a proximal centriole. The hepatocytes facing the bile passage possessed no cilium, although they frequently had a diplosome in their apical cytoplasm. The single cilia of the bile ductular epithelium gradually tapered toward the tip. The original fiber pattern in the most proximal part was peripheral 9 doublets +0. In the ciliary shaft, the doublets altered into singlets which were diminished in number gradually toward the distal parts of the shaft, so that in the tip only one singlet remained. Since these fiber patterns in the single cilia markedly deviated from the 9 + 2 fiber pattern of the ordinary motile cilia, they may not be motile, but properly regarded as sensory or chemoreceptors.

Ultrastructural changes of bile duct epithelium in primary biliary cirrhosis in relation to progression of bile duct loss

Using wedge liver biopsies from patients with primary biliary cirrhosis (PBC), ultrastructural features of the intrahepatic bile ducts in livers with slight or no bile duct loss were compared with those in livers with advanced bile duct loss and in extrahepatic cholestasis (EHC). Most changes in the biliary epithelium in PBC were similar to those in EHC. Microvillous loss and bleb formation, mitochondrial damage and increase in endoplasmic reticulum and ribosomes were found in PBC irrespective of the degree of bile duct loss, and also in EHC. These changes were present almost equally at any level of the biliary tree, and are presumed to represent a variety of non-specific lesions of biliary epithelial cells. As the loss of bile ducts in PBC progressed, cytoskeletal filaments and cytophagosomes increased in number and basement membranes were more thickened and reduplicated. These changes were more or less conspicuous in smaller branches of the biliary tree, and were also prominent in EHC. They might be causally related to the bile flow disturbance in the liver. Lateral intercellular spaces were irregularly dilated and contained osmiophilic membranous and/or granular material, similar to that found in duct lumena, within and without the basement membrane, and in the cytoplasm of periductal macrophages. Furthermore, pinocytotic vesicles were increased in the biliary cytoplasm facing periphery. These findings suggest possible alteration of the permeability of biliary epithelial cells, probably in the direction from the lumena to the periductal tissue. Such changes were found in PBC livers with virtual absence of bile duct loss, and the significance of this phenomenon is discussed.

Electron microscopy of liver lesions in primary biliary cirrhosis. I. Intrahepatic bile duct oncocytes

Liver biopsy specimens from a primary biliary cirrhosis (PBC) patient and two control patients with other biliary disorders were examined under the electron microscope, with special reference to intrahepatic bile ducts. The PBC patient had a bile duct with an 80 micrometers diameter that showed specific alterations in epithelial cells. These cells were termed oncocytes, and their main features were: the presence of a large number of swollen mitochondria with abnormal cristae, no mitochondrial bodies, small number of exocrine granules and an undulated nucleus with a large cytoplasm. The number of mitochondria per ultrathin-sectioned epithelial cell was greater by about 2 times in the oncocytic epithelial cells compared to the control cells. Fine fibrils and long-spacing collagens were present around the PBC bile duct. Periductal capillaries of the bile duct had multilayered basement membranes. These periductal changes may have induced the oncocytic changes in the epithelial cells. The basement membrane of the bile duct was meandrous and often disrupted, but not multilayered. Many lymphocytes and macrophages infiltrated among the epithelial cells.

A scanning and transmission electron microscopic study of experimental extrahepatic cholestasis in the rat

The rat liver after extrahepatic biliary obstruction was studied by SEM and TEM in correlation with basic histochemical techniques. Cholestasis was verified by serological methods. The biochemical data (increase in serum bilirubin values, a gradual lowering of the albumin fraction), in agreement with the ultrastructural results of a sparse RER, suggested a gradual decrease of the protein synthetic activity of the hepatocyte. SEM and TEM revealed numerous fat-storing cells, closely associated with patches of connective fibrils in the subendothelial spaces. Further ultrastructural observations demonstrated: a) a proliferation of the intrahepatic biliary tree (ductular proliferation, including newly formed ducts with sacculation and diverticuli); b) an increased number of canaliculo-ductular junctions and, c) an increase in the length of the bile canalicular network due to its tortuous course, pocketing and side branching. The occurrence of an intact cytoplasmic barrier separating the bile canalicular lumen from the Disse's space together with the results obtained by retrograde infusion of ferritin into the biliary tree suggested that the regurgitation pathway by ductular reabsorption and by transhepatocytic transport is the best documented and most acceptable, at least in the rat.

Ultrastructural lesions of bile ducts in primary biliary cirrhosis. A comparison with the lesions observed in graft versus host disease

Intrahepatic bile duct destruction is a characteristic feature of primary biliary cirrhosis and hepatic graft versus host disease. Lymphocytotoxicity against antigens on the surface of biliary cells is one of the cell mediated immune mechanisms debated in the pathogenesis of persistent bile duct destruction during primary biliary cirrhosis. Immune complex injury has also been hypothesized. In graft versus host disease, damage to bile duct cells is also believed to be due to a cytotoxic reaction of the grafted lymphoid cells against the host histocompatibility antigens, and immune complex deposition is likely to occur. The aim in this comparative ultrastructural study of intrahepatic bile ducts in 10 patients with primary biliary cirrhosis and six patients with hepatic graft versus host disease was to investigate whether identical or different ultrastructural lesions were detected in both diseases. Features of conspicuous necrosis of biliary cells, including cytolysosomes, apoptosis, and basement membrane disruption, were observed in both diseases. Numerous lymphocytes established close membrane contacts with biliary cells, especially with the necrotic ones. They had cytoplasmic pseudopods, and some of them displayed a uropod or contained lysosomal vesicles. Abnormalities of the bile duct basement membrane, also observed in both diseases, included thickening or multilayering and numerous lucent areas of rarefaction often containing osmiophilic inclusions. The striking similarity of the ultrastructural lesions in both diseases provides an additional morphological argument to suggest that certain common pathogenic mechanisms might be involved in the destruction of bile ducts in primary biliary cirrhosis as well as in hepatic graft versus host disease.

A scanning electron microscopic study of the liver of the monkey Macaca speciosa. II. Intra- and extrahepatic biliary system

The bile canalicular network of the monkey was studied by fracturing fixed liver tissue and examination by scanning electron microscopy. Bile canaliculi do not differ remarkably from those described in other species. Their course and luminal diameter vary, depending on their position in the liver lobule. In one specimen the continuity of a canaliculus with a terminal bile ductule (canal of Hering) is presented. Several constrictions occur in this part of the ductular lumen. The interlobular bile duct wall shows two kinds of niches. A single cilium arises from a primary niche. The walls of secondary niches contain numerous primary niches. Simple columnar epithelium lines the common bile duct, the main pancreatic duct and the Several constrictions occur in this part of the ductular lumen. The interlobular bile duct wall shows two kinds of niches. A single cilium arises from a primary niche. The walls of secondary niches contain numerous primary niches. Simple columnar epithelium lines the common bile duct, the main pancreatic duct and the Several constrictions occur in this part of the ductular lumen. The interlobular bile duct wall shows two kinds of niches. A single cilium arises from a primary niche. The walls of secondary niches contain numerous primary niches. Simple columnar epithelium lines the common bile duct, the main pancreatic duct and the gallbladder. A common feature is the presence of microplicae on their lateral cell surfaces.

Data concerning the histogenesis of intrahepatic biliary ducts in human embryofetal life

The development and histostructural organization of intrahepatic biliary ducts were studied on a human embryofetal material 6 to 32 weeks old. These formations appeared during the whole study period, in close connexion with the extension of the portal vasculo-connective spaces. In the epitheliomesenchymal contact area, the liver cells of limiting plates possessing an increased histogenetic plasticity will generate, through a metamorphosis process, the bordering epithelia of intrahepatic biliary structures.

Pericanalicular hepatocytic and bile ductular microfilaments in cholestasis in man

The cytoplasmic microfilaments of hepatocytes in the pericanalicular area and of bile ductular cells in various types of human cholestasis were examined and compared with those seen in the noncholestatic human liver. An increase in the number of hepatocytic microfilaments with an increase in the apparent density of the filamentous network and in the thickness of bundles of filaments was evident in the vicinity of the bile canaliculi, in the pericanalicular ectoplasm, and in the surrounding cytoplasm in all types of cholestasis but more so in intrahepatic cholestasis. This increase in the number of microfilaments was also seen around undilated canaliculi. Microfilaments were also increased in number beneath the surface of the bile ductular cells facing the cytoplasm but not beneath the rest of the plasma membrane. More microfilaments also were found around ductular cell nuclei. No striking differences were noted between intrahepatic and extrahepatic cholestasis. These findings suggest that microfilaments play a role that is not established in human cholestasis.

A scanning electron microscopic study on the liver of mice

The three-dimensional fine structures of several tissue components of the liver in normal mice were studied by scanning electron microscopy. The tissue components observed were as follows: hepatocytes, sinusoidal endothelial cells, the Kupffer cells, fat-storing cells, reticulin fibers and epithelial cells of the bile duct. Two types of fenestrations were found in the sinusoidal endothelial cells. One was smaller and clustered, and the other larger and scattered. Both of them were distributed equally throughout the hepatic lobule. Intercellular gaps were found at the endothelial junction. The Kupffer cell which was localized in a large gap between the endothelial cells was characterized by numerous villous projections, and by the absence of fenestrations which were observed in the endothelial cells. Fat-storing cells were located between hepatocytes. They elongated their processes into the space of Disse, but never protruded into the sinusoidal lumen. They were clearly distinguished from the endothelial cells and the Kupffer cells by their morphological feature and location. No transitional form was seen among the endothelial cells, the Kupffer cells, and the fat-storing cells.

A scanning electron microscopic study on hepatic changes induced by mouse hepatitis virus-2

No significant changes in the structure of the liver were seen until 9 hr after the inoculation of mouse hepatitis virus-2 (MHV-2) into mice. At the 24 hr stage, distinct swelling of hepatocytes and narrowing of sinusoidal lumina were observed from the middle to the central area of the hepatic lobules. Most of the Kupffer cells were swollen. Their villous projections were decreased in number, and the remaining projections became like blebs. Virus particles appeared from this stage in the hepatocytes, the Kupffer cells and the space of Disse. At the 48 hr stage, parenchymal necrotic foci were present in the central and the middle area of the lobules. The necrotic change was increased from 72 hr after inoculation, and was followed by submassive or massive necrosis. It is suggested that hepatic necrosis in both the central and the middle area, or in either area, of the lobules was advanced by aggravation of the sinusoidal microcirculation, as a result of the swelling of the hepatocytes and the Kupffer cells in addition to the direct affection by virus. Fine granulation was observed on the surface of most of the central flagella of the bile duct. Some flagella were degenerated, and came in part to be a fibrillar net.

A three-dimensional study of organelle interrelationships in regenerating rat liver. 3. Organelles related to bile

A number of cell structures are described which show a morphological relationship to the bile canaliculi. Two types of peribiliary vesicles are identified: osmication positive ones occurring between the bile canaliculi and the osmicated immature Golgi cisternae and probably deriving from the latter, and osmication negative ones related to MVB, on which they appear as buds. Small coated vesicles are seen attached to this second type. Large lacunae may originate from MVB, as suggested by the MVB-like internal vesicles they may contain. Some stay in luminal continuity with the bile canaliculi. Canalicular coated vesicles are seen as parts of the canalicular plasma membrane and free in the cytoplasm.

The transport by hepatocytes of immunoglobulin A from blood to bile visualized by autoradiography and electron microscopy

Polymeric myeloma IgA, labelled with 125I, was injected intravenously into rats that were killed 5, 30, or 60 min later and the livers removed, fixed and sectioned. Autoradiographs of ultra-thin sections examined in the electron microscope showed that the IgA first became bound to the plasma membrane of the hepatocytes but after 30 min much of it was transported across their cytoplasm and became localized around the bile canaliculi. At this time, autoradiographs of 1 micrometer sections examined in the light microscope showed the contents of the bile ducts in the portal tracts to be labelled heavily. These results confirm the previous finding of rapid transport of IgA across the liver and show directly that the hepatocytes are the cells that carry it out. No intracellular organelle or vesicular structure, discernible within the resolving power of the techniques used, could be implicated in the transport mechanism.

Acute fine structural changes in rat hepatocytes induced by a single large dose of 2-acetylaminofluorene

Male rats were given a single intragastric dose of 2-acetylaminofluorene, 600 mg/kg body weight, killed at intervals up to 14 days after treatment, and their hepatic tissue examined by electron microscopy. The early cytoplasmic lesion produced in hepatocytes by lower doses, consisting of perinuclear glycogen pooling, peripheral displacement of organelles and pyknosis, was delayed for several days. Among the changes which appeared to be independent of this lesion were disorganization and decrease of the granular endoplasmic reticulum and abnormalities of the bile canaliculi. These changes were similar to those which are seen during chronic exposure to 2-AAF and other hepatocarcinogens and in hepatic cell tumours.

[The value of needle biopsy of the liver in the differential diagnosis of cholestatic jaundice. A clinico-pathologic study of 101 cases (author's transl)]

The examination of needle biopsy of the liver has permitted the identification of the aetiology of cholestatic jaundice in eighty five cases out of a series of one hundred-and-one patients, leaving eight without definite diagnosis and eight false diagnosis. The characteristic histopathologic lesions of lobular hepatitis and of obstructive jaundice are reviewed. The problems of identification of particular microscopic forms (obstructive jaundice with minimal portal tracts alterations, residual stage of hepatitis, cholangiolitic and hypercholestatic forms of hepatitis) are discussed.

The paracellular pathway and bile formation

Choleretic infusions of taurocholate (40 μ moles for one hour) result in a significant increase in the number of lateral cell surface invaginations observed by scanning electron microscopy adjacent to the junctional complex of bile canaliculi in rat liver. Transmission electron microscopy indicates that these invaginations resemble "blisters" induced by osmotic gradients across epithelial tissues, a morphologic change which correlates with increases in ionic and hydraulic conductivity of the paracellular "shunt" pathway in such tissue. Since taurocholate infusions result in localization of ionic lanthanum chloride within hepatocyte junctional complexes, bile acids may also stimulate the movement of fluid and electrolytes across paracellular pathways during the process of bile formation.

Morphological and functional changes in the tight junctions of the bile canaliculi induced by bile duct ligation

Thin sections after bile duct ligation showed that the depth of tight junctions appeared to increase and that the distance between individual punctate contacts appeared to become irregular and wider than in controls. The freeze fracture replicas clearly demonstrated these changes in the tight junction morphology. Changes were noted most conspicuously in the tight junction three weeks after ligation. Measurements of the junctional morphology in control and ligated specimens showed that the junctional depth had increased two fold in the latter, whereas the number of strands had scarcely changed. Lanthanum tracer experiments showed that the tight junctions did not permit the passage of the tracer in normal nor ligated rats. It was concluded that the mechanism of obstructive jaundice could not be related to changes in junctional morphology causing increased junctional permeability.

Sclerosing cholangitis associated with ulcerative colitis. Light and electron microscopy studies

The light and electron microscopy findings of liver biopsies from four patients with sclerosing cholangitis and ulcerative colitis are described. The main histologic feature was mesenchymal proliferation involving phagocytic, fibroblastic and immunocytic cells suggestive of an immunologic type of liver injury which may attack bile duct epithelial cells. Other histologic features, included the presence of myelin fibers in both hepatocytes and bile duct epithelial cells and an abundant amount of lysosome-like structures. The significance of these findings is discussed.

Evidence for microfilament involvement in norethandrolone-induced intrahepatic cholestasis

An experimental study of norethandrolone (NED)-induced intrahepatic cholestasis was made. NED was infused via a portal vein catheter into rat liver in vivo, and measurements were made of bile flow. Liver specimens were taken at intervals for light microscopy and for transmission and scanning electron microscopy. Bile-canalicular-rich membrane fractions were prepared. The effects of NED were also examined in isolated hepatocytes in suspension culture. NED infusion induced total cholestasis by 3 hours. Canalicular alterations commonly associated with cholestasis were found in in vivo infused liver and in isolated hepatocytes. Pericanalicular microfilament changes were also noted in both, with loss of filament structure and replacement by a granular zone. In isolated canalicular membrane fractions prepared from NED-treated animals, the normal investment of pericanalicular filaments was no longer present. Loss of the bile canalicular ruthenium red surface coat was also noted. In view of the identical findings in isolated hepatocytes and in in vivo liver, obstruction and mechanical factors can be excluded as possible causes. The results raise the possibility that the mechanism of NED-induced cholestasis may be related to disaggregation and/or detachment of microfilaments from the canalicular membranes.

Transmission electron microscope observation of epithelial cells with single cilia in intrahepatic biliary ductules of bats

Cells with long single cilia arising from basal bodies in the apical cytoplasm were occasionally revealed in the bile ductular epithelia of bats (Miniopterus schreibersi (Kuhl), Myotis macroductylus (Temminck) and Rhinolophus cornutus (Temminck)). The basal body (distal centriole) was associated witha proximal centriole, so the basal structure was of "two centriole type." In cross sections of the long tapering cilia the arrangement of cilary microtubules was determined. In the most proximal portion of the cilia doublet microtubules were arranged in the 9+0 pattern, while in more distal portions alteration and diminution of the doublet fibers occurred, splitting entirely into single microtubuli which were most frequently rearranged in the 6+1 or 7+1 pattern. The occurrence of the 9+0 fiber pattern and the basal structure of "two centriole type" suggested that the biliary ductular cilia might be sensory or chemoreceptive in nature and not motile. Similar cilia are expected to be found distributed widely in the epithelia of excretory ductal system of large exocrine glands of vertebrate species.

Cholesterol in acute cholestasis induced by taurolithocholic acid. A cytochemical study in transmission and scanning electron microscopy

Rats were given intravenous injections of a single dose of sodium taurolithocholate, and an almost total cholestasis appeared after 10 minutes and lasted for 3 hours after the injection; then the choleresis began again and 24 hours after the injection, normal values of bile flow were restored. Ultrastructural analysis of the liver during the acute cholestasis and the restoration phase showed, beside usual modifications found in most cases of cholestasis, the "characteristic" alterations of sodium taurolithocholate-induced cholestasis. Cytochemical procedures were used, both in transmission and in scanning electron microscopy, in order to delineate the possible participation of free cholesterol in these cellular modifications. After Williamson's reaction procedure (Williamson JR:J Ultrastruct Res 27:118, 1969), not only were cholesterol-digitonin complexes found in large numbers, both in the hepatocytic cytoplasm and in the biliary canaliculi, but also their morphologic appearance revealed several new features: dark sticks and dark lamellae, frequently adsorbed on the outer surface of crystalline clear material were observed by transmission electron microscopy, and plugs, obliterating parts of biliary canaliculi, were observed using scanning electron microscopy. These observations seem to indicate that a significant amount of free cholesterol is released into the hepatocyte cytoplasm and into canalicular lumina within a few minutes after the infection of sodium taurolithocholate, probably originating from the hepatocytic membranes, especially from those limiting the canalicular lumen. Such a drastic modification in the chemical constitution of these membranes should coincide with a marked modification of their active and passive transport ability.

A cilia-bearing cell system in the intrahepatic bile ductules of the rat

A scanning electron microscopic investigation of the luminal surface of the intrahepatic bile ducts of the rat has been performed using tissue prepared by critical point drying. Results of these studies have demonstrated that intrahepatic bile ducts of the rat are composed of cells, the luminal surface of which contains either microvilli or numerous long cilia. It was suggested that these cilia play an important role in tissue function, particularly in the propulsion of hepatic bile.

Liver ultrastructure in psoriatics related to methotrexate therapy. 2. Findings in bile ducts from 11 methotrexate treated psoriatics and 2 controls

To determinate what damage occurred in the bile ducts of psoriatics receiving Methotrexate (MTX) therapy liver biopsies from 11 patients were studied with the light and electron microscope and compared with normal material. Thick sections (1 micrometer) showed light and dark cells in biliary epithelium and lipofuscin granules. At the ultrastructural level these were confirmed. The lumen of the bile ducts contained debris. The microvilli were decreased in number and damaged forms appeared. Damage to the biliary epithelial mitochondria was widespread and there were foci of intracellular oedema. The Golgi apparatus was hypertrophied and dilated. Atrophic cells were seen. The lateral intercellular spaces were dilated and contained debris and the basement membrane showed zones of duplication. Similar changes were found in the ducts of Hering.

Subcellular pathology of rat liver in cholestasis and choleresis induced by bile salts. 1. Effects of lithocholic, 3beta-hydroxy-5-cholenoic, cholic, and dehydrocholic acids

Cholestasis or choleresis was induced in the rat by intravenous infusion (0.05 to 0.2 mumole per minute per 100 grams of body weight) of sodium taurolithocholate, 3beta-hydroxy-5-cholenoate, taurocholate, and dehydrocholate either singly or in combination after or without cannulation of the common bile duct. Bile flow was monitored and ultrastructural changes were examined by scanning and transmission electron microscopy up to 3 hours after bile salt administration. Taurolithocholate induced acute cholestasis and ultrastructural alterations consisting primarily of dilation of bile canaliculi, loss of canalicular microvilli, and lamellar transformation of the canalicular membrane. Occasionally, crystalline precipitates were present within the canalicular lumen and in the pericanalicular region of hepatocytes. 3beta-Hydroxy-5-cholenoate caused similar but less severe ultrastructural changes than those induced by taurolithocholate. Dehydrocholate had a greater choleretic effect than taurocholate, but neither induced noteworthy ultrastructural change. When infused simultaneously with taurolithocholate, taurocholate reversed cholestasis and largely prevented development of the ultrastructural changes induced by taurolithocholate. In contrast, simultaneous infusion of dehydrocholate prevented neither cholestasis nor development of the ultrastructural changes induced by taurolithocholate, which were more striking than those caused by taurolithocholate or 3beta-hydroxy-5-cholenoate alone. In addition, structural changes associated with cholestasis induced by these bile salts either singly or in combination were more pronounced and frequent in the periportal zone than elsewhere in the hepatic lobule. These results suggest that both taurolithocholate and 3beta-hydroxy-5-cholenoate induce cholestasis by affecting the structural and functional integrity of the bile canalicular membrane and also, in part, by forming untransportable precipitates. The contrasting effects of taurocholate and dehydrocholate on taurolithocholate-induced changes suggest that taurocholate overcomes the effect of taurolithocholate by solubilizing it into mixed micelles, but dehydrocholate and its metabolites have little or no such effect. The intralobular variation in severity of ultrastructural changes probably reflects the accumulation of bile salts in greater concentrations in hepatocytes near the portal triads.

Effects of chronic choleretic infusions of bile acids on the membrane of the bile canaliculus. A biochemical and morphologic study

To determine whether choleretic infusions of bile acids modified the function or structure of the membrane of the bile canaliculus, sodium taurocholate (NaTc) or dehydrocholate (DHC) was infused into male rats at a rate of 80 mumoles per hour over an 18-hour period. Bile was collected by fistula and phospholipid and cholesterol content was measured in bile, liver homogenates, and isolated liver plasma membranes (LPM) enriched in bile canaliculi. Na+, K+-ATPase, Mg2+-ATPase, 5'-nucleotidase, and alkaline phosphatase activities were also measured in LPM. NaTc infusions enhanced cholesterol and phospholipid output in the bile in association with a significant increase in phospholipid in both LPM and liver homogenate. Although DHC infusions resulted in a comparable excretion of bile acid, phospholipid and cholesterol output in bile did not increase from control values and the concentration of these lipids in LPM and liver homogenate also did not change. However, LPM Na+, K+-ATPase significantly increased after DHC infusions compared to NaTc-infused animals or controls. Neither bile acid altered the activities of Mg2+-ATPase, 5'-nucleotidase, or alkaline phosphatase. Both bile acids increased the diameter of the lumen of the bile canaliculus as assessed by scanning electron microscopy and produced irregularities and outpouchings in the canalicular membrane. Diverticuli and loss of microvilli were most prominent with DHC infusions whereas canalicular side branching and the density of microvilli, either remained unchanged or increased following NaTc infusions. Although the morphologic findings are qualitative, the results of these studies indicate that chronic choleretic infusions of NaTc and DHC have divergent effects, not only on enzyme activities in liver plasma membrane, but on phospholipid composition and 3-dimensional structure. These findings suggest that bile acids may after biliary secretion not only through their osmotic effects, but by modifying lipids and enzymes in the membrane of the bile canaliculus.

Experimental porphyria induced by 3-(2,4,6-trimethylphenyl)-thioethyl)-4 methylsydnone

Administration of 3-[2-(2,4,6-trimethylphenyl)-thioethyl]-4-methylsydnone (TTMS) induces hepatic porphyria in rats, mice and dogs. The protoporphyrin pigment in livers of rats and mice is found mainly in bile ducts and leads to bile duct proliferation and portal inflammation. Dog livers contain protoporphyrin predominantly in bile canaliculi. The birefringence of the pigment appears to be associated with bilamellar components within the pigment. The markedly depressed catalase activity in livers of rats does not increase after clofibrate administration. The catalase activity of mouse liver is depressed slightly and responds to clofibrate treatment.

Cholangiodysplastic pseudocirrhosis: light and electron microscopic examination

The familial type of cholangiodysplastic pseudocirrhosis is presented. This chronic liver disease is caused by malformation of the intrahepatic bile ducts. The female infant was 5 months old when the diagnosis was established. The liver biopsy was studied by light and electron microscopy. Electron microscopic examination revealed active proliferation of ductual cells and progression of fibrogenesis, findings consistent with the rapid and fatal course of the disease. In the case presented an acute cholangitis occurred, but after healing the progression of the original process led to hepatic insufficiency. It is suggested that cholangiodysplastic pseudocirrhosis is a chronic, progressive liver disease the course of which might be hastened by the complication of cholangitis; the process itself causes liver cirrhosis without inflammation.

Characterization of rat liver cell plasma membranes

A method is described by which bile canalicular membranes (BCM) can be prepared, together with canaliculus-free plasma membrane (PM), both essentially free of contamination. The recovery of both fractions together was estimated to be 46%. The concentrations of total lipid, total phospholipid and cholesterol were substantially greater in the BCM, and polyacrylamide gel electrophoresis revealed differences in protein composition. The differences in lipid and protein composition of these two plasma membrane fractions are presumably related to their very different physiological functions.

Scanning electron microscopy of the rat liver. Studies of the effect of taurolithocholate and other models of cholestasis

The normal surface anatomy of rat hepatocytes, sinusoids, and bile canaliculi was examined by scanning electron microscopy following finger fracture of tissues that were perfused via the portal vein and fixed with 2.5% glutaraldehyde. These normal findings were contrasted with several models of cholestasis, including infusion of sodium taurolithocholate (TLC), bile duct ligation, and ethynyl estradiol treatment, in order to examine the effects of cholestasis on morphology of the bile canaliculus. TLC-induced cholestasis was associated with specific dilation and disruption of canalicular membranes, which corresponded to evaginations of pericanalicular ectoplasm observed by transmission electron microscopy, and suggested a direct toxic effect of the bile salt on membrane structure. Infusions of lithocholate sulfate or simultaneous infusions of TLC and sodium taurocholate prevented these severe abnormalities from occurring. Bile duct ligation produced progressive canalicular dilation (from 1 to 96 hr) and loss of microvilli, but did not result in the type of membrane changes produced by TLC. No significant changes in canalicular morphology were observed following ethynyl estradiol treatment. These studies demonstrate that scanning electron microscopy is a useful technique for the evaluation of both normal and abnormal hepatic surface morphology, and indicate that TLC produces a distinctive abnormality in the structure of the canalicular membrane, which was not seen in other models of cholestasis.