Development of extrahepatic bile duct excluding gall bladder in human fetuses: histological, histochemical, and immunohistochemical analysis.

BACKGROUND: The fetal development of extrahepatic bile ducts (EBD) is unkown. MATERIALS AND METHODS: Development of EBD was examined by immunohistochemistry in 16 fetuses of 7-40 gestational week (GW). Gall bladder (GB) was not investigated. RESULTS: At seven GW, a hepato-pancreatic bud (HPB) was seen near the hepatic hilus. At eight GW, embryonic EBD, GB and pacreas developed from HPB. Portal veins (PV) and hepatic arteries (HAs) were present in EBD at eight GW. Liver parenchyma was already present in seven GW. At eight GW, EBD at porta hepatis (PH) was already established; PH EBD was derived from ductal plate (DP). The distal and middle EBD gradually develeped and took shape of EBD at nine GW. In PH, cystic and hepatic ducts developed from DP at eight GW. EBD developed further, accompanying many nerve fibers (NF) at PH and distal and middle EBD. Apparent PV and HA were seen around 12 GW. Around 20 GW, HA and capillaries proliferated, giving rise to peribiliary capillary plexus (PCP) in all parts of EBD. EBD grew gradually further, and around 30 GW extrahepatic peribiliary glands (EPG) emerged from EBD but not from cystic duct. Around 36 GW, exocrine pancreatic acinar cells emerged from remodeled DP at PH. At term (40 GW), EBD was established but was as yet immature. Numerous NF were present around EBD. Histochemically, EBD epithelium had no mucins at 7-12 GW but contained neutral and acidic mucins at 23-40 GW. EPG had abundant neutral and acidic mucins. Immunohistochemically, alpha-fetoprotein (AFP) was consistently positive in the epithelial and mesenychyma. The NF and muscles of HPB present at seven GW were positive for neural cell adhesion molecule (NCAM), neuron-specific enolase (NSE), platelet-derived growth factor receptor-α (PDGFRA), and KIT, but they disappeared in nine GW. Expressions of cytokeratin (CK) seven and CK19 in EBD and EPG were slight or none, while expression of CK8 was moderate, and that of CK18 was strong. NF were positive for NCAM, NSE, synaptophysin, and chromogranin, and PDGFRA. MUC1 and MUC6 apomucins were noted in EBD and EPG. EPG contained numerous endocrine cells positive for chromogranin, synaptophysin, NCAM and NSE. A few endocrine cells positive for these antigens were seen in EBD. Numeous KIT-positive stem cells (SC) were seen in PH, EBD, PV, HA, PCP, and EPG. NCAM-positive and bcl-2-positive SC were also located in these structures. Epithelial cells of EBD and EPG showed expressions of MET, PDGFRA, CA19-9, MUC1, MUC2, MUC6, KIT, bcl-2, and ErbB2. No expressions of HepPar1, carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA) were noted. CONCLUSIONS: Although the findings have limitatios because this study of humans are descriptive one, the present data suggest that the processes of the development and differentiation of EBD system may be associated with EBD SC, CK prolifes, SFC/KIT signaling, HGF/MET signaling, PDGRa/PDGFRA signaling, fibroblast growth factor/ErbB2 signaling, neuroendocrine lineage, NF differentiation, pancreatic aninar cell differentiation, PCP differentiation, MUC apomucins differentiation, and expressions of AFP and CA19-9. HepPar1, EMA and CEA were not involved in them.

Anatomic variations of extrahepatic bile ducts and evaluation of the length of ducts composing the cystohepatic triangle / Variaciones anatómicas de los ductos biliares extrahepáticos y longitud de los ductos del trígono hepato-cístico

It is of paramount importance for surgeons to have a thorough knowledge of the normal anatomy of the extrahepatic bile ducts and its variations due to the high frequency with which they perform in this anatomic site. The cystohepatic triangle, or Calot's Triangle, is bound by the cystic duct, common hepatic duct, and the hepatic border; therefore, its surface area depends on the conformation of these ducts and is closely linked to surgical procedures performed in this region. It has been reported that the length and the position of these ducts may be related to the formation of bile duct stones, Mirizzi's syndrome, and bile duct cancer. Thus, the present work aims to analyze the configuration of the extrahepatic biliary tree and its possible variations, as well as measure the components that make up the cystohepatic triangle. For this task 41 samples from fixated human cadavers were analyzed, with 25 consisting of anatomic parts (liver and biliary tree) and 16 in situ samples. The extrahepatic biliary trees were dissected in order to measure the length of the common hepatic and cystic ducts with a digital caliper, and all anatomic variations were registered. The length of the common hepatic duct varied between 4.18 mm and 50.64 mm, with an average of 21.76 +/- 9.51 mm. The length of the cystic duct varied between 7.28 and 38.88 mm, with an average of 19.11 +/- 6.77 mm. Anatomic variations were found in 3 samples (7.3 percent): in one of them the cystic duct connected to the left hepatic duct; in another, the cystic duct connected to the right hepatic duct; in the third, there was a triple confluence of hepatic ducts (two right ducts and one left duct). The results are a contribution to the clinical and surgical anatomy of this region.

El conocimiento de la anatomía normal de las vías biliares extrahepáticas y sus variaciones es fundamental para los cirujanos digestivos debido a la frecuencia con que se actúa en esa región. El trígono hepato-cístico o de Calot es delimitado por el ducto cístico, ducto hepático común y el margen del hígado. De este modo, su área depende de la conformación de esos ductos y está íntimamente relacionada a procedimientos quirúrgicos efectuados en esa zona. Se ha señalado que la longitud y la disposición de esos ductos estarían involucradas en la formación de cálculos biliares, síndrome de Mirizzi y neoplasias de vías biliares. Así, el presente estudio tuvo como objetivo analizar la configuración de las vías biliares extrahepáticas y sus posibles variaciones, además de registrar parámetros métricos de los componentes del sistema biliar que integran el trígono hepato-cístico. Para el estudio se utilizaron 41 muestras de cadáveres formolizados de individuos adultos, siendo 25 piezas anatómicas (de hígado y vías biliares) y 16 in situ. Las vías biliares fueron disecadas, esquematizadas y fotografiadas, se registró la longitud del ducto hepático común y cístico con un caliper digital. La longitud promedio del ducto hepático común fue de 21,76 +/- 9,51 mm, variando de 4,18 mm a 50,64 mm; la longitud promedio del ducto cístico fue de 19,11 +/- 6,77 mm, variando de 7,28 a 38,88 mm. Se observaron variaciones en 3 muestras (7,3 por ciento), en una de ellas, el ducto cístico se unió al ducto hepático izquierdo, en otra, el ducto cístico se unió al ducto hepático derecho y en la otra muestra, se presentó una confluencia triple de ductos hepáticos, dos derechos y uno izquierdo. Los resultados obtenidos son un aporte a la anatomía clínica y quirúrgica de la región.

Microvascularization of the canine hepatic ducts.

The angioarchitecture of the proximal and distal segments of the hepatic duct in the dog was investigated by means of vascular corrosion casts under a scanning electron microscope. The results of observations indicated a change of the pattern of vascularization of the hepatic duct along with the increasing distance of the hepatic duct from the liver and increasing diameter of the duct. In the proximal hepatic duct, the main blood vessels run along the duct as a pair of supplying arteriole and voluminous collecting venule, while in the distal segments of the hepatic duct on the opposite margin of the duct two vascular triads were observed, composed of two venules and one medial arteriole. On the surface of both segments of the hepatic duct, there are well-anastomosed outer venous plexuses. In the distal segments of the hepatic duct, the outer venous plexus accompanies a fine outer arterial rete. Observations of the intramural network indicate the presence of single terminal arterioles running to mucosa and supplying a subepithelial capillary network. Differences were observed in the blood drainage from the mucosa, as in the proximal segment of the hepatic duct single post-capillary venules are found, while in the distal segment in the mucosa a well-developed mucosal venous plexus is formed. In the well-developed venous system of the hepatic duct no valves were observed.

Morphological and histological study of the ostrich (Struthio Camelus L.) liver and biliary system.

The peculiarity of the digestive system of the ostrich (Struthio Camelus L.), which is characterized by the continuous production of bile, led us to undertake macroscopical and histological studies of the liver and its biliary system, since very little bibliographic data exist on the subject. For this purpose we observed the organs of male and female ostriches 16-18 months of age, in situ, in order to describe their location, relationships and morphology. Samples of the liver were processed for observation by light microscopy; samples of the hepatoenteric duct were processed for observation by light and electron microscopy. Our findings regarding the liver revealed the presence of two lobes: a left lobe, subdivided into three lobes, and a right undivided lobe. There was no gall-bladder. The histological picture showed unlimited hepatic lobules, with hepatocytes arranged in cord-like fashion two cells thick. A large hepatoenteric duct arose from the porta hepatis, and opened into a papilla in the descending limb of the duodenum. The mucosa of the duct was lined by simple columnar epithelium consisting of cells having the same morphological cytoplasmatic features but distinguished by either a light or a dark nucleus.

Characterization of ductular hepatocytes in end-stage cirrhosis.

The existence of facultative stem cells in the liver has been advocated based on observations from models of carcinogenesis in rat liver. Observations of human liver material from cases of fulminant hepatitis have shown the presence of ductular hepatocytes expressing markers of both hepatocytes and bile duct cells. We describe the morphologic features and antigenic expression of a population of ductular hepatocytes identified in a patient with end-stage cirrhosis resulting from hepatitis B infection and secondary biliary cirrhosis. By conventional light microscopy and electron microscopy, ductular hepatocytes were seen to form pseudoductules within periportal areas. Using immunohistochemical methods, these ductular hepatocytes were found to be positive for both the hepatitis B surface antigen and bile duct epithelial cytokeratin, phenotypic markers classically restricted to expression on hepatocytes and bile duct epithelium, respectively. These findings show definitively that ductular hepatocytes are intermediate cells bearing morphologic and phenotypic characteristics of both hepatocytes and bile duct epithelium. The presence of these cells indicates the existence of facultative stem cells in the adult mammalian liver.

Somatostatin-containing cells in the extrahepatic biliary tract of humans.

We investigated the presence of endocrine cells in the human extrahepatic biliary system using the avidin-biotin-peroxidase complex method. Twenty gallbladders obtained during operations for cholelithiasis, large portions of three common bile ducts obtained during Whipple's procedure for carcinoma of the head of the pancreas, and 155 endoscopic transpapillary biopsy specimens taken during control endoscopy from patients who had had a previous endoscopic sphincterotomy were examined. Somatostatin-containing cells were found in the glandular epithelium of the ampulla of Vater and the bile ducts. Only the surface epithelium in the ampulla contained endocrine cells. All somatostatinlike immunoreactivity was confined to cells and could not be detected in nerves. No somatostatinlike immunoreactivity was found in the gallbladder. These findings reveal a morphologic basis to reported actions of somatostatin on bile flow.

The musculature of the gall bladder and biliary pathways in the guinea-pig.

A study of the gall bladder and the biliary pathways was carried out in the guinea-pig by light and electron microscopy. The musculature of the distended gall bladder measures only about 220 microns in thickness and consists of muscle bundles running in various directions. The muscle cells are loosely packed and are much smaller than the muscle cells of the intestinal muscularis externa. They resemble, in structure and arrangement, the cells of the muscularis mucosae of the intestine. In the cystic duct, the hepatic duct and the upper third of the bile duct, the musculature is similar to that of the gall bladder but is sparser and mixed with abundant connective tissue (fibromuscular layer). In the middle and lower portions of the bile duct there is a progressive increase in the amount of musculature. While the outer diameter of the organ remains constant (about 1.3 mm), the amount of muscle in a transverse section of the duct increases more than ten times along the length of the duct. Here the muscle cells are large and densely packed and closely resemble those of the duodenal muscularis externa. The bile duct forms with the duodenum an angle of about 30 degrees and it opens into a large cavity within the duodenal wall, the ampulla, which has a complex muscular system of its own. The ampulla is drained into the duodenal lumen through a duct within the papilla, around which lies a ring of circular musculature. The pancreatic duct opens independently into the duodenum about 6 cm aboral to the bile duct.

[The fine structure of the epithelium of the main outlets from the liver and pancreas of the domestic chicken (author's transl)]. / Die Feinstruktur des Epithels der Hauptausführungsgänge der Leber und des Pankreas vom Haushuhn.

Light- and electronmicroscopic and some histochemical investigations on the major excretory ducts of pancreas and liver was carried out on 24 adult chicken. The epithelium of both ducts was shown to include: cells with apical secretory granules, non-differenciated duct cells, ciliated cells and migrating cells. In addition the epithelium of the pancreatic ducts included goblet cells. The distal plasmalemm and the microvilli are covered with surfacecoat, which like the secretory granules produces precipitate with PA-silver. This area of the cell also shows a strong reaction to M++ and Ca++ activated ATPase.

Some observations on the morphological evidence for mechanism of the bile secretion.

The morphological evidence of the intracellular route of bile secretion was investigated in the liver of goldfish (Carassius auratus) as revealed by electron microscopy. Smooth surfaced tubules or cisterns within or adjacent to the Golgi apparatus showed linear saccular forms and contained sparse particulate or cloudy materials of low electron density. The isolated vacuoles were restrictedly found between the Golgi apparatus and the intracellular bile canaliculus or hepatocytic side at the zone of transition. These vacuoles showed no reaction for acid phosphatase activity, and contained only a few cloudy materials similar to those found in the saccular tubules and within the bile canaliculus. Some of these vacuoles fused with the luminal cytolemmas of the bile canaliculus. Bases on these findings, it was assumed that these vacuoles are structures participating in transport and secretion of bile constituents and derive from the linearly sacculated tubules or cisterns in the Golgi zone. Duct cells showed no morphological evidence to suggest bile secretion.

A demonstration of microvilli on the luminal surfaces of epithelial cells of the canine extrahepatic biliary tract.

Micromorphologic evidence is presented which indicates that in the dog the lining epitheliums of the intramural portion of the common bile duct and proximal part of the cystic duct are organized into convoluted folds. The mucosal lining of the extramural portion of the common bile duct appears to contain simple crypt structures. The mucosal surface of the hepatic duct is characterized by parallel ridges, longitudinally aligned with the long axis of the duct. The epithelial cells of the entire canine extrahepatic biliary tree present a topographic-dome shaped appearance, and their luminal surfaces are densely covered with microvilli.