A novel imaging tool for hepatic portal system using phase contrast technique with hydrogen peroxide-generated O2 gas.

The objective of this study was to investigate the potential of hydrogen peroxide-generated oxygen gas-based phase contrast imaging (PCI) for visualizing mouse hepatic portal veins. The O2 gas was made from the reaction between H2O2 and catalase. The gas production was imaged by PCI in real time. The H2O2 was injected into the enteric cavity of the lower sigmoid colon to produce O2 in the submucosal venous plexus. The generated O2 gas could be finally drained into hepatic portal veins. Absorption contrast imaging (ACI) and PCI of O2-filled portal veins were performed and compared. PCI offers high resolution and real-time visualization of the O2 gas production. Compared with O2-based ACI, O2-based PCI significantly enhanced the revealing of the portal vein in vivo. It is concluded that O2-based PCI is a novel and promising imaging modality for future studies of portal venous disorders in mice models.

Interobserver variability of ultrasound parameters in portal hypertension.

The aim of this study was to assess interobserver agreement of ultrasound parameters for portal hypertension in hepatosplenic mansonic schistosomiasis. Spleen size, diameter of the portal, splenic and superior mesenteric veins and presence of thrombosis and cavernous transformation were determined by three radiologists in blinded and independent fashion in 30 patients. Interobserver agreement was measured by the kappa index and intraclass correlation coefficient. Interobserver agreement was considered substantial (kappa = 0.714-0.795) for portal vein thrombosis and perfect (kappa = 1) for cavernous transformation. Interobserver agreement measured by the intraclass correlation coefficient was excellent for longitudinal diameter of the spleen (r = 0.828-0.869) and splenic index (r = 0.816-0.905) and varied from fair to almost perfect for diameter of the portal (r = 0.622-0.675), splenic (r = 0.573-0.913) and superior mesenteric (r = 0.525-0.607) veins. According to the results, ultrasound is a highly reproducible method for the main morphological parameters of portal hypertension in schistosomiasis patients.

Interobserver variability of ultrasound parameters in portal hypertension

The aim of this study was to assess interobserver agreement of ultrasound parameters for portal hypertension in hepatosplenic mansonic schistosomiasis. Spleen size, diameter of the portal, splenic and superior mesenteric veins and presence of thrombosis and cavernous transformation were determined by three radiologists in blinded and independent fashion in 30 patients. Interobserver agreement was measured by the kappa index and intraclass correlation coefficient. Interobserver agreement was considered substantial (ê = 0.714-0.795) for portal vein thrombosis and perfect (ê = 1) for cavernous transformation. Interobserver agreement measured by the intraclass correlation coefficient was excellent for longitudinal diameter of the spleen (r = 0.828-0.869) and splenic index (r = 0.816-0.905) and varied from fair to almost perfect for diameter of the portal (r = 0.622-0.675), splenic (r = 0.573-0.913) and superior mesenteric (r = 0.525-0.607) veins. According to the results, ultrasound is a highly reproducible method for the main morphological parameters of portal hypertension in schistosomiasis patients.

A light and transmission electron microscope study of hepatic portal tracts in the rhesus monkey (Macacus rhesus).

This study reports on morphological features of hepatic portal tracts in the liver of a rhesus monkey. The light microscope shows that the number of each type of principal component comprising a portal tract varies but that there are usually one to five lymphatics, one bile ductule, one bile duct, one arteriolar and one arterial branch of the hepatic artery, and one hepatic portal vein. Bile ductules, in cross section, have 6-10 cells (mostly low pyramidal, but with a few cuboidal) bordering the lumen, an outside diameter of from about 20 to 25 microm, and a luminal diameter of from 2 to 10 microm. Bile ducts, in cross section, have more than 10 cells (about equal numbers of low pyramidal and cuboidal) bordering the lumen, an outside diameter greater than 25 microm and a luminal diameter of greater than 10 microm. The term "pyramidal" has not previously been applied to the cells of the ductules and ducts. The monkey tracts show several cytological features previously undescribed, viz., abortive cilia and basal bodies in the duct cells, abortive cilia in the ductule cells, and an occasional aggregation of ribosomes in arterial endothelial cells. They also show a major histological feature previously mentioned but not illustrated, viz., bundles of nerve processes which exhibit a preferential location, i.e., proximity to the arterioles and arteries.

Role of apoptosis in the remodeling of cholestatic liver injury following release of the mechanical stress.

It has been known for a long time that portal fibrosis consecutive to experimental common bile duct ligation is reversible following obstacle removal, but the mechanisms involved remain unknown. We have studied the effect of bilioduodenal anastomosis and of simple biliary decompression on the remodeling of the lesion in bile duct-ligated rats. Rats were subjected to common bile duct ligation for 7 days or 14 days. Bilioduodenal anastomosis was performed after 14 days of bile duct ligation and animals sacrificed at intervals. In other animals, after 7 days or 14 days of ligation, the common bile duct was merely decompressed by bile aspiration and animals sacrificed 24 h later. Collagen deposition, alpha-smooth muscle actin expression and apoptosis were evaluated. Bile was collected and the bile acid profile assessed. After anastomosis, collagen deposition and alpha-smooth muscle actin expression decreased and were back to control values after 7 days. These parameters remained practically unchanged 24 h after biliary decompression. Bile duct ligation by itself induced apoptosis of some fibroblastic and bile ductular cells after 7 days; this was back to normal after 14 days. After anastomosis or decompression, apoptosis of both fibroblastic and bile ductular cells increased greatly and was accompanied by ultrastructural features of extracellular matrix degradation. Total bile acid content decreased after common bile duct ligation, the proportion of dihydroxylated bile acids decreasing and that of trihydroxylated bile acids increasing. Biliary decompression and anastomosis did not modify total concentration and composition of the biliary bile acid pool. In summary, we show that mere biliary decompression, by relieving the mechanical stress, is as effective as bilioduodenal anastomosis to induce apoptosis of portal cells that likely triggers portal fibrosis regression.

Doppler study of mesenteric, hepatic, and portal circulation in alcoholic cirrhosis: relationship between quantitative Doppler measurements and the severity of portal hypertension and hepatic failure.

To determine the relationship between quantitative Doppler parameters of portal, hepatic, and splanchnic circulation and hepatic venous pressure gradient (HVPG), variceal size, and Child-Pugh class in patients with alcoholic cirrhosis, we studied forty patients with proved alcoholic cirrhosis who underwent Doppler ultrasonography, hepatic vein catheterization, and esophagoscopy. The following Doppler parameters were recorded: time-averaged mean blood velocity, volume flow of the main portal vein flow, and resistance index (RI) of the hepatic and of the superior mesenteric artery. Doppler findings were compared with HVPG, presence and size of esophageal varices, and Child-Pugh class. There was a significant inverse correlation between portal velocity and HVPG (r = -.69), as well as between portal vein flow and HVPG (r = -.58). No correlation was found between RI in the hepatic artery or superior mesenteric artery and HVPG. No correlation was found between portal vein measurements and presence and size of varices. Severe liver failure was associated with lower portal velocity and flow. In patients with alcoholic cirrhosis, only portal vein blood velocity and flow, but neither hepatic nor mesenteric artery RI, are correlated to the severity of portal hypertension and to the severity of liver failure.

Observations on the fine structure of the liver in the camel (Camelus dromedarius).

The structure of macroscopically inconspicuous livers in 23 adult camels (Camelus dromedarius) was studied by light and transmission electron microscopy. A well-developed connective tissue characterizes the camel liver. Thick trabeculae divide the liver parenchyma into lobules. Portal tracts and central veins are surrounded by a variable amount of fibrous tissue. In the perisinusoidal space (DISSE), collagen fibres form a dense three-dimensional network around the sinusoids. A mild to moderate fatty infiltration is present in hepatocytes of all animals. In the epithelial cells of the bile ducts, small to medium sized lipid inclusions are a common feature. The ultrastructure of hepatocytes in the camel liver corresponds to that of other domestic mammalian species. The endothelial cells lining the sinusoids show a multiple fenestration and are surrounded by a discontinuous basal lamina. Fat-storing cells are numerous and contain lipid droplets varying in size, number and electron density from one cell to another.

Comparative analysis of insulo-acinar portal system in rats, guinea pigs, and dogs.

The insulo-acinar portal system in the rat, guinea pig, and dog was comparatively analyzed using corrosion casting method in scanning electron microscopy and confocal laser scanning microscopy. In all animals examined, there were three types of arterioles according to their destination: 1) the arteriole which supplied the capillary glomerulus of the islet, 2) the arterioles which directly branched out into capillaries around the acini, and 3) the arterioles which supplied the duct system. In the rat, the afferent vessel usually ended in the cortical layer of the islet and its main branches ran along this layer before giving secondary capillary branches into the deeper regions, while in the dog and guinea pig, the region where the afferent arterioles branched out into secondary capillary branches varied among individual islets. There were three types of efferent vessels of the islet: 1) the insulo-acinar portal vessels that radiated from the islet to join the capillary network in the exocrine pancreas, 2) the emissary venules of the islet, leading directly into the systemic circulation, and 3) the insulo-ductal portal vessels which drained into the peri-ductal capillary network. In the rat and guinea pig, the intralobular islets possessed both the insulo-acinar portal vessels and the emissary venules, while the interlobular islets possessed emissary venules with occasionally occurring insulo-acinar portal vessels. In the dog, most of the islets were located within the lobule and possessed preferentially the insulo-acinar portal vessels. In this animal, the lobule was supplied by several microvascular units, in the center of which was located the capillary glomerulus of the islet. The peri-insular zone of the unit was mainly supplied by the insulo-acinar portal vessels, while the periphery, the tele-insular zone, was directly supplied by arterioles as well. The venules originated at the periphery of the unit. The islet in the dog had virtually no emissary venules. Confocal laser scanning microscopy of the rat islets showed that B cells occupied the core of all islets. The microvascular architecture within the rat islet appeared to be organized as to drain blood from the A and D cell area to the B cell area of the islet.

Blood flow patterns in the rat pancreas: a simulative demonstration by injection replication and scanning electron microscopy.

Scanning electron microscopy of vascular casts prepared by arterial injections of intentionally reduced amounts of resin showed that in the rat pancreas, the casting medium fills blood capillaries in the endocrine islets more promptly than those in the exocrine lobules and secretory ducts. Furthermore, the exocrine lobules containing endocrine islets allowed a more rapid resin flow through the insulo-acinar portal route than those lobules lacking an islet. The capillaries of secretory ducts were the last portions to be filled with resin. Since the resin used in this study was as viscous as blood and injected under a physiological pressure, the microcirculatory patterns demonstrated by the present method reflect the physiological flow pattern of blood in the pancreas.

Pancreatic insulo-acinar portal systems in humans, rats, and some other mammals: scanning electron microscopy of vascular casts.

Scanning electron microscopy of vascular casts showed that in the mouse, rat, and guinea pig, the pancreatic endocrine islets were frequently interlobular in position and emitted insulo-venous efferent vessels directly draining into veins. In these animals, the intralobular islets, located within the exocrine lobules, issued insulo-acinar portal vessels continuous with the lobular capillaries in addition to the insulo-venous efferent vessels. In humans, monkeys, cows, pigs, dogs, cats, and rabbits, essentially all islets in the pancreas were intralobular in location and emitted the insulo-acinar portal vessels only. In man and animals examined, especially in the murine species, many lobules lacked an islet, therefore the insular control over the exocrine pancreas seemed to be effected in more or less restricted areas of lobules.

Proliferation and phenotypic modulation of portal fibroblasts in the early stages of cholestatic fibrosis in the rat.

The animal model of hepatic fibrosis induced by bile duct ligation represents an experimental model of human chronic biliary fibrosis. Much attention has been given to the hepatic stellate cell (HSC), or perisinusoidal cell, as the source of the extracellular matrix proteins. However, in the bile duct ligation model, mesenchymal cells other than HSC may be involved in the early stages of fibrosis development. The current study examined, in Sprague-Dawley rats, proliferation in different liver cell subpopulations as well as expression of alpha-smooth muscle (SM) actin and desmin in portal fibroblasts and HSC at 6 hours and 1, 2, 3, and 7 days after bile duct ligation. Kinetics of liver cell proliferation and of phenotypic modulation of portal fibroblasts and HSC (expression of alpha-SM actin and desmin) was evaluated by immunocytochemistry, immunofluorescence, and immunoelectron microscopy using immunogold technique. In sham-operated animals, the evaluation of proliferation in various liver cell subpopulations revealed nonsignificant changes compared with nonoperated rats. alpha-SM actin was detected in vessel walls but was absent in cells of portal tract and parenchyma. Desmin was expressed in vessel walls and in some fibroblastic cells of portal stroma (8.2 cells/unit area) as well as in HSC in acinar Zones 1 and 3 (15.6 cells/unit area and 7.1 cells/unit area, respectively). In bile duct-ligated rats, 24 and 48 hours after ligation, marked proliferations of bile duct epithelial cells (labeling indices 36.8% and 29.5%, respectively) and of periductular fibroblasts (labeling indices 16.7% and 31.0%, respectively) were observed; thereafter, proliferation decreased for both populations (labeling indices at 7 days 12.0% and 11.6%, respectively). HSC proliferation increased gradually until the third day (labeling index 18.6%) and then leveled off. Immunocytochemistry and immunoelectron microscopy revealed a significant number of cells expressing alpha-SM actin 72 hours after bile duct ligation in the stroma adjacent to proliferating ductules. The number of alpha-SM actin-positive cells increased until the seventh day (251.6 cells/unit area). At all times examined, the distribution of alpha-SM actin was restricted to the connective tissue stroma adjacent to proliferating ductules; alpha-SM actin was not expressed in HSC of the lobule. An expansion of desmin expression was noted in fibroblastic cells in stroma surrounding proliferating ductules until 72 hours after bile duct ligation (74.7 cells/unit area) followed by a plateau. At this time, desmin expression increased also in HSC; as in controls, the number of positive cells was greater in Zone 1 (31.8 cells/unit area) than in Zone 3 (18.5 cells/unit area). Double immunofluorescence staining detected by confocal microscopy showed that the majority of portal fibroblastic cells expressing alpha-SM actin was desmin negative 48 hours after bile duct ligation. From 72 hours, portal fibroblastic cells coexpressing alpha-SM actin and desmin appeared, and their proportion increased until 7 days. The present findings indicate that in the early phase of bile duct ligation, there is a marked and transient proliferation of bile duct epithelial cells associated with proliferation of portal periductular fibroblasts, which rapidly express alpha-SM actin. This fibroblastic population may play a dominant role in the early portal fibrosis after bile duct ligation.

The protective effect of portoarterial shunts after experimental hepatic artery embolization in rats with liver cirrhosis.

PURPOSE: The role of the portal system after hepatic artery embolization (HAE) was examined. METHODS: Using a Wistar strain rat model of liver cirrhosis, the route and occurrence of portoarterial (PA) shunts before and after HAE by scanning electron microscopic (SEM) and histologic methods were evaluated. HAE was performed with iodized oil and gelatin sponge particles. RESULTS: In the SEM study, PA shunts did not develop in normal rats regardless of whether they did (n = 10) or did not have HAE (n = 5). The cirrhotic rat model showed PA shunts in both HAE (n = 5) and non-HAE (n = 5) animals. PA shunts were established via the peribiliary plexus and direct arterioportal anastomosis. In the histologic study, the occurrence of PA shunts in liver cirrhosis was significantly increased by HAE (HAE = 6, non-HAE = 6, p < 0.01). CONCLUSION: The development of PA shunts, which help perfuse liver parenchyma, may explain why HAE can be safely performed in patients with liver cirrhosis.

Phenotypic change in portal fibroblasts in biliary fibrosis.

Portal fibroblasts have been considered responsible for biliary fibrosis. Since lipocytes show differentiation toward myofibroblast-like cells in hepatic fibrogenesis, we studied whether similar differentiation of portal fibroblasts could be observed in biliary fibrosis. We examined rat livers after bile duct ligation by double immunofluorescent staining of alpha-smooth-muscle actin (alpha-smA) and desmin and also by electronmicroscopy. In the portal tract of normal livers, alpha-smA-positive cells were noted only in the vessel wall, whereas desmin-positive cells were occasionally seen in the connective tissue as well. With the development of biliary fibrosis, alpha-smA was remarkably expressed in the portal connective tissue, while desmin was seen in a small portion of alpha-smA-positive cells around proliferating bile ducts. In normal livers, portal fibroblasts presented quiescent features, such as a small Golgi complex and a few cisternal profiles of endoplasmic reticulum under electron microscopy. After 7 days of bile duct ligation, portal fibroblasts proliferated, were arrayed in multilayers, and were associated with collagen bundles. Some of these fibroblasts had numerous cytoskeletal components, and developed rough endoplasmic reticulum and a dense body. These data suggest that portal fibroblasts appear to differentiate toward myofibroblasts in biliary fibrosis.

Topography of short portal vessels in the rat pituitary gland: a scanning electron-microscopic and morphometric study of corrosion cast replicas.

We applied scanning electron microscopy combined with imaging and morphometric techniques to analyze the dorsal topography and morphology of short portal vessels linking the capillary beds of the pituitary neural and anterior lobes in adult male albino rats. The pituitary microvasculature was replicated by intracarotid injection of Batson's No. 17 compound producing plastic casts that were advantageous for comprehensive morphometric analyses using an imaging device. The analysis revealed the existence of two types of portal vessels having quantitatively different morphological properties. The bilateral venular plexus of 3-4 vessels located at the base of the infundibular stalk (each venule measuring 300 microns in length and 32 microns in diameter) appears to be the major part of the short portal system in the dorsum of the rat pituitary gland. Narrower capillary-like shunt vessels (6.8 microns in diameter), of about the same length as the venules, were situated throughout other subregions of the intermediate lobe cleft. The short portal vessels of both types made direct anastomoses with the capillary networks in the neural and anterior lobes. The neural lobe capillaries were twice as numerous (1324 per mm2), and only half as wide (6.2 microns), as the sinusoidal capillaries in the anterior lobe (density of 637 per mm2; diameter of 13.7 microns). The topographical position of the portal venular system suggests that the caudolateral subregions of the pituitary neural and anterior lobes have a functional relationship dependent on rapid interlobe transfer of neurohumoral factors such as hormones via the portal blood. This process appears to be supplemented throughout the rest of the cleft between the two lobes by a small number of capillary shunts that supply the epithelial cell lobules of the intermediate lobe in situ. The findings collectively indicate that this portal system provides a constant stream of neurohumoral information that is shared moment-by-moment between the pituitary neural and anterior lobes.

Microcirculation of the rat pancreas, with special reference to the insulo-acinar portal and insulo-venous drainage systems: a further scanning electron microscope study of corrosion casts.

Microcirculation in rat pancreas was studied by scanning electron microscopy of resin vascular casts and by light microscopy of India ink-injected and sectioned tissue samples. In the scanning survey of the casts, islets larger than 30 microns in diameter counted no less than 400 in the adult rat pancreas. They were located either in the exocrine lobules (intralobular islets, counting 210 or more), or in the interlobular tissue spaces and along the secretory ducts (extralobular islets, 190 or more). Every islet received arterial blood via one or more proper arterioles. These afferent vessels first divided in the peripheral zone of the islet consisting of A and D cells and later extended deeper to form a capillary network in the islet core consisting of B cells. Blood originating from this capillary network left the islet via efferent vessels. This microvascular pattern may favor the regulation by A and D cells over the secretory activity of B cells. The intralobular islets gave their efferent vessels to the capillary bed of the exocrine tissue of the lobule, thus forming an insulo-acinar portal system. When the lobule was relatively small in size, superfluent blood was led directly to veins via insulo-venous drainage vessels. The intralobular islets sometimes issued one or more long translobular portal vessels reaching adjacent lobules. The extralobular islets issued either insulovenous vessels draining to interlobular veins, or extralobular insulo-acinar portal vessels supplying adjacent lobules.

The blood vascular bed of the human pancreas, with special reference to the insulo-acinar portal system. Scanning electron microscopy of corrosion casts.

Microdissection and scanning electron microscopy of corrosion casts showed the structures of the vascular bed of the human pancreas to consist mainly of the capillary plexuses of the exocrine lobules, extralobular ducts and endocrine islets. A considerable number of the exocrine lobules were found to contain one to four marked endocrine islets larger than 30 microns in diameter. These intralobular islets received one or more arterioles (afferent vessels) and emitted conspicuous insulo-acinar portal vessels which continued into the lobular capillaries, suggesting insular control over the functions of the exocrine acini of the pancreas. Direct drainage of the intralobular islets into the veins was never reproduced. Not excluding the possibility that some lobules might contain smaller, unidentifiable islets, there nonetheless were many lobules which directly received arterioles. These lobules are free of control by an islet. Rarely, an islet was located in the interlobular tissue space or along an extralobular duct. Such an extralobular islet issued no portal vessels, and drained into the interlobular or periductal veins. The surface of this type of islet comprised a thin network of fine capillaries. A possibility was suggested that this cortical network might be homologous with the lobular capillaries. No portal route was observed between the islets and extralobular ducts. Few connections were noted between the capillary plexuses of the lobules and ducts.

[Light and scanning electron microscopic study on portal circulation of the pancreas in the monkey].

The channel of microcirculation in the exocrine and endocrine parts of the pancreas in 20 monkeys (Macaca Mulatta) were studied by scanning electron microscopy (SEM) and light microscopy (LM). The results revealed that there are portal circulations between the endocrine and exocrine parts in the pancreas of monkey. The direction of the blood flow is from the endocrine to the exocrine part: arteriole----sinusoid of the islet----portal vessel----acinar capillaries----venule. There are "insulo-insular portal system" and "convergent insulo-acinar portal system" in pancreas of these monkeys. This is for the first time reported. The functional and clinical significances of pancreatic portal circulation are discussed.

[The formation of the insulo-acinar portal system in the pancreas of human fetuses]. / Formirovanie insulo-atsinarnoi portal'noi sistemy v podzheludochnoi zheleze plodov cheloveka.

In human fetuses 12-20-week-old peculiarities in creation and development of the pancreatic hemo-microcirculatory bed have been studied in connection of its incretory part formation. The vascular glomerulus begins to form on the 12th-14th week as transformation of capillaries of the exocrinic parenchyma into the glomerular capillaries, which, on their getting out of the glomeruli, turn into vessels. The latter participate in formation of the insulo-acinar portal system. Certain structures have been revealed for adaptation of an elevated volume of the blood stream in the glomeruli place, where the glomerular microvessels pass into the acinar anastomoses. The latter perform shunting of the glomerular capillaries with the arteriole, which brings blood, enriched in insular hormones, to distantly situating acinar cells.