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.

Closure of the cystic duct by ultrasonic energy: an electron-microscopic and biomechanical study in man.

BACKGROUND: Ultrasonic activated devices are currently used both for sealing of blood vessels and dissection of parenchymal organs. Recently, ultrasonic energy has been used to seal the cystic duct during successful clip-less cholecystectomy, but no study examined the mechanisms of tissue welding by ultrasonic energy or the biomechanical properties of the seal. This was the aim of our investigations. PATIENTS AND METHODS: Eight patients (7 women and 1 man, mean age 42+/-7 y) subjected to laparoscopic cholecystectomy had a cystic duct sealed and sectioned by Ultracision; after removal of the specimens, the distal end was processed for scanning electron microscopy and transmission electron microscopy, whereas the proximal end to the gallbladder was used for determination of the bursting pressure. RESULTS: The bursting pressure of the cystic duct sealed by ultrasonic energy was 168+/-47 mm Hg, well above the maximal pressure of the common bile duct. At scanning electron microscopy, the end of the cystic duct was closed by an amorphous, bundled, dense substance. The section proximal to the end showed destruction of the epithelial layer with dense amorphous bridges connecting the opposite sites of the wall. When the lumen was observed, it was filled with bile microaggregates. At transmission electron microscopy, 2 different findings were evident: (1) coagulative necrosis in the sectioned area and (2) a combination of coagulative necrosis and collagen denaturation in the more distal sections. The connective tissue was characterized by attenuation of collagen birefringence and swelling of fibers and bundles due to shrinkage of collagen. CONCLUSIONS: Ultrasonic energy can be applied to suitable tissues to obtain sealing of the walls with good biomechanical effects.

Carcinoma in situ of the cystic duct.

Cholelithiasis and cholesterolosis associated with carcinoma in situ of the cystic duct epithelium was observed in a male patient. Ultrastructurally, small acini-like lined a thickened, reduplicated basal lamina encompassing a pleiomorphic population of cells, including typical cholecystocytes, a poorly differentiated type, and cells containing modified mucous vesicles with heterogeneous fatty deposits. Even though the etiology of this apparent neoplastic epithelium and of its thickened basal lamina is unclear, it is hypothesized to be the result of an altered control of cell adhesion mechanisms, resulting from a repeated renewal of the typical epithelium abraded by the passage of the stones and the biliary sludge, associated with inflammatory stimuli that accompany cholecystolithiasis. Based on recent studies, it is suggested that investigations of molecular markers in extrahepatobiliary tract lesions and retrospective studies of these archival tissues could clarify the association of these neoplastic changes with other hepato-biliary lesions.

The mechanisms of blood vessel closure in humans by the application of ultrasonic energy.

BACKGROUND: The use of the ultrasonically activated scalpel (UAS) for vessel closure has attained widespread acceptance in many surgical fields. The aim of our study was to investigate the electron microscopic changes to the blood vessels after the application of UAS. METHODS: We collected 10 arterial and 10 venous segments from vessels that had previously been closed by UAS during abdominal operations. The samples were then prepared for ultramicroscopic analysis. Pathological changes in the lumen and the three wall layers of the blood vessel were examined under scanning and transmission electron microscopy. RESULTS: All of the vessel segments showed similar changes: the presence of a blood clot, endothelial cell condensation, coagulative necrosis of the wall, and charring of the vessel at its tip. The edge of the cut vessel were closed by the coagulation bond, which was tied up by collagen fibrils escaped from denaturation. CONCLUSION: When ultrasonic energy is applied to tissues, it changes their structure so as to make a new extracellular matrix.

Ultrastructural aspects of human cystic duct epithelium as a result of cholelithiasis and cholesterolosis.

Although there is a large body of data on the gallbladder and the importance of the cystic duct in surgical procedures, there is insufficient data regarding the morphology of the human cystic duct. In the present study, transmission electron microscopic (TEM) and scanning electron microscopic (SEM) survey of several surgical and autopsy cystic ducts in cholelithiasis and cholesterolosis is reported. In cholelithiasis, similar to gallbladder epithelium, the cystic duct epithelial cells display minor-to-severe alterations of the epithelial surface accompanied by variable erosion of the epithelium. Areas of intact surface epithelium demonstrate microvilli-covered cells coated by a rich glycocalyx and mucous production. In other areas, apical excrescences are associated with mucus hyperproduction and secretory events. Lipoid bodies are also present in many cells and especially in many of the cells' subliminal apical areas. In cholesterolosis, mucous secretory granules appear dilated, fatty deposits are infrequent, and peculiar intracellular cholesterol deposits can be detected in the apical and subapical region of cells and around condensed mitochondria. Following elective cholecystectomies, predominantly in association with cholelithiasis, eroded areas were detected; therefore, it appears that the action of intraluminal calculi may be a principal causative factor in discrete epithelial erosions of the cystic duct. Intraluminal calculi/ debris, along with the alteration of mucus, cell sloughing, and a decreased pool of bile acids and motility may participate in the gallstone nucleation process. The peculiar cholesterol inclusions may also play a role in that nucleating process.

Ultrastructural changes of female Syrian hamster cystic duct epithelium as a result of sex steroid treatment.

In view of the lack of sufficient data regarding the morphology of the cystic duct and the extensive focus on the gallbladder, a preliminary examination of the cystic duct response to female sex steroid treatment was conducted to follow up a detailed ultrastructural study of the gallbladder epithelial response to a similar treatment. As observed in the gallbladder epithelium, the cystic duct epithelial cells of nulliparous Syrian hamsters demonstrate morphologic changes in response to female sex steroid treatment. Control (C) cystic duct epithelial cells are covered by short microvilli and each cell appears to exhibit a single vestigial cilium. Estrogen (E)- and estrogen + medroxyprogesterone (E + MP)-treatments induce differential duct cell morphologic changes. These changes are the result of steroid treatments in the significant decreasing sequence E > E + MP > C for nuclear volume, indentations and perinuclear lysosomal/lipofuscin bodies. Moreover E + MP-treatment results in larger cytoplasmic volume and more sloughing of apical cell excrescences than following E treatment. It is suggested that, similar to that in the gallbladder, the action of progestin is paramount in favoring cytoplasmic morphological changes in the cystic duct which, along with the alteration of mucus, cell sloughing, decreased bile acids and motility could also participate in the gallstone nucleation process as they are brought into the gallbladder with the incoming bile flow.

Morphology of the prairie dog gallbladder: normal characteristics and changes during early lithogenesis.

Studies were undertaken to describe the normal structure of the prairie dog gallbladder and adjacent cystic duct, and then to determine sequential changes that occurred as abnormalities in bile composition developed during high cholesterol feeding. Control animals were fed a diet with trace cholesterol, while experimental animals were fed a diet enriched with 1.2% cholesterol for 1, 2, 3, or 4 weeks. Light microscopy and scanning and transmission electron microscopy were used to characterize morphologic changes at each time interval. Biliary lipid composition was altered in all experimental groups, evidenced by significant decreases in bile-acid-to-cholesterol ratios. Cholesterol crystals appeared in experimental bile at 1 and 2 weeks, while stones formed at 3 and 4 weeks. The cystic duct and neck of the gallbladder occasionally displayed goblet cells. Little mucus was demonstrable in principal cells of the gallbladder, but much more in those lining the cystic duct. After 2 weeks of lithogenic diet, there was an increase in mucus content and secretion from all areas, as well as an influx of polymorphonuclear and mononuclear leukocytes. Accumulation of plasma cells in the lamina propria was an especially prominent feature of experimental tissues. These results suggest that 1) there is regional heterogeneity in the mucus content of the gallbladder and cystic duct of the prairie dog, and 2) both regions respond to lithogenesis with mucus hypersecretion and acute and chronic inflammatory changes prior to the appearance of cholesterol gallstones.

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.

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.