Abdominal ultrasound in amazonian manatee (Trichechus inunguis) (Natterer, 1883) / Ultrassonografia abdominal em peixe boi amazônico (Trichechus inunguis (Natterer, 1883)

Morphophysiological species researches are fundamental, and diagnostic imaging is an excellent technique, already used in wild animals, with great application, not invasive and provide real-time information of each body. Amazonian manatees are on the list of endangered animals classified in the vulnerable category and knowledge of the normal pattern of ultrasound anatomy of organs and tissues is important for the maintenance and well-being of captive specimens contributing to reintroduction actions. The objective of the study was to standardize the examination technique and describe the ultrasound findings of the liver, gallbladder, stomach, urinary bladder and the subcutaneous tissue of the abdominal region in Trichechus inunguis, in order to contribute with the anatomical and sonographic knowledge and assist in the diagnosis and prognosis diseases. The study used 18 animals to describe the normal sonographic anatomy in the abdominal cavity of the Amazonian manatee. During abdominal scan, it was possible to visualize the features of the liver, gallbladder, stomach, urinary bladder obtained satisfactory results in this study. Therefore, other structures were not primarily identified by the reduced time, lots of fat and gases in intestines of animals.

Pesquisas morfofisiológicas em espécies selvagens são fundamentais, e o diagnóstico por imagem é uma excelente técnica, já usada e com grande aplicação, não invasiva e que fornece informações em tempo real de cada órgão. Peixes-boi-amazônico encontram-se na lista de animais ameaçados de extinção classificados na categoria vulnerável e o conhecimento do padrão normal da anatomia ultrassonográfica de órgãos e tecidos é importante para a manutenção e bem-estar de espécimes em cativeiro contribuindo para ações de reintrodução. O objetivo deste estudo foi padronizar a técnica de exame e descrever os achados ultrassonográficos do fígado, vesícula biliar, estômago, vesícula urinária e o tecido subcutâneo da região abdominal em Trichechus inunguis, de modo a contribuir com o conhecimento anátomo-sonográfico e auxiliar no diagnóstico e prognóstico de doenças. O estudo utilizou 18 animais para descrever a anatomia ultrassonográfica normal na cavidade abdominal de peixe-boi amazônico. Durante a varredura abdominal foi possível visualizar as características dos órgãos obtendo resultados satisfatórios neste estudo, concluindo ser uma técnica eficiente para avaliação de determinados órgãos abdominais em peixe-boi amazônico. Entretanto, outras estruturas não foram identificadas principalmente pelo tempo reduzido, muita gordura e gases nos intestinos dos animais.

Oncogenic KRAS-expressing organoids with biliary epithelial stem cell properties give rise to biliary tract cancer in mice.

Biliary tract cancer (BTC) arises from biliary epithelial cells (BECs) and includes intrahepatic cholangiocarcinoma (IHCC), gallbladder cancer (GC), and extrahepatic cholangiocarcinoma (EHCC). Although frequent KRAS mutations and epigenetic changes at the INK4A/ARF locus have been identified, the molecular pathogenesis of BTC is unclear and the development of corresponding anticancer agents remains inadequate. We isolated epithelial cell adhesion molecule (EpCAM)-positive BECs from the mouse intrahepatic bile duct, gallbladder, and extrahepatic bile duct, and established organoids derived from these cells. Introduction of activated KRAS and homozygous deletion of Ink4a/Arf in the cells of each organoid type conferred the ability to form lethal metastatic adenocarcinoma with differentiated components and a pronounced desmoplastic reaction on cell transplantation into syngeneic mice, indicating that the manipulated cells correspond to BTC-initiating cells. The syngeneic mouse models recapitulate the pathological features of human IHCC, GC, and EHCC, and they should therefore prove useful for the investigation of BTC carcinogenesis and the development of new therapeutic strategies. Tumor cells isolated from primary tumors formed organoids in three-dimensional culture, and serial syngeneic transplantation of these cells revealed that their cancer stem cell properties were supported by organoid culture, but not by adherent culture. Adherent culture thus attenuated tumorigenic activity as well as the expression of both epithelial and stem cell markers, whereas the expression of epithelial-mesenchymal transition (EMT)-related transcription factor genes and mesenchymal cell markers was induced. Our data show that organoid culture is important for maintenance of epithelial cell characteristics, stemness, and tumorigenic activity of BTC-initiating cells.

A histological and histochemical study on the gallbladder of the Alburnus tarichi (Güldenstädt, 1814) (Cyprinidae) / Estudio histológico e histoquímico de la vesícula biliar de Alburnus tarichi (Güldenstädt, 1814) (Cyprinidae)

In the current study, the histological structure of the gallbladder of Alburnus tarichi (Güldenstädt, 1814) was investigated. Hematoxylin and eosin were used to stain the histological sections for routine examinations, in addition to using periodic acid Schiff (PAS) for the neutral mucins, aldehyde fuchsin (AF) for the sulphated mucins, and Alcian blue (AB; pH: 2.5) for the acidic mucins. In addition, proliferating cell nuclear antigen (PCNA) immune-staining was performed for the detection of dividing cells among the epithelium. The gallbladder of A. tarichi was composed of mucosa, muscularis, and serosa or adventitia layers. The mucosa covering the wavy pleomorphic folds was made up of tall columnar epithelium and a lamina propria. The apical surface of the epithelial cells was lined by continuous short microvilli. On the epithelium, the luminal surface was remarkably stained with PAS, AF, and AB. Slight to moderate staining was observed on the epithelial cells in the apical zone with PAS. The cytoplasm of epithelial cells were stained in a slight manner with AF. No goblet cells were observed among the epithelium. According to the PCNA immune-staining, some epithelial cells were observed to proliferate. The lamina propria consisted of loose connective tissue that contained fibrocytes, collagen and elastic fibers, capillaries, and small blood vessels. The muscularis layer displayed muscle fibers that were circular, smooth, and surrounded by collagen fibers. The subserosal and serosal or adventitial layers had typical morphology to those of other fish and vertebrates.

En este estudio, se investigó la estructura histológica de la vesícula biliar de Alburnus tarichi (Güldenstädt, 1814). Las secciones histológicas se tiñeron con Hematoxilina-Eosina para los exámenes de rutina, además de usar el ácido periódico de Schiff (PAS) para las mucinas neutras, aldehído fucsina (FA) para las mucinas sulfatadas y azul alcián (AB; pH: 2,5) para las mucinas ácidas. Además, se realizó una tinción inmune de antígeno nuclear de células proliferativas (PCNA) para la detección de células en división entre el epitelio. La vesícula biliar de A. tarichi estaba compuesta de capas, mucosa, muscular y serosa o adventicia. La mucosa que cubría los pliegues pleomórficos ondulados estaba formada por un epitelio columnar alto y una lámina propia. Se observó una superficie apical de las células epiteliales revestida por microvellosidades cortas y continuas. En el epitelio se observó una tinción importante de la superficie luminal teñida con PAS, FA y AB. Se observó una tinción leve a moderada en las células epiteliales en la zona apical con PAS. El citoplasma de las células epiteliales se tiñó ligeramente con FA. No se observaron células caliciformes entre el epitelio. Según la tinción de PCNA, se observó que proliferaban algunas células epiteliales. La lámina propia consistía en tejido conectivo laxo que contenía fibrocitos, colágeno y fibras elásticas, capilares y pequeños vasos sanguíneos. La capa muscular mostraba fibras musculares circulares, lisas y rodeadas de fibras de colágeno. Las capas subserosas y serosas o adventicias tenían una morfología típica a la de otros peces y vertebrados.

Core Hippo pathway components act as a brake on Yap and Taz in the development and maintenance of the biliary network.

The development of the biliary system is a complex yet poorly understood process, with relevance to multiple diseases, including biliary atresia, choledochal cysts and gallbladder agenesis. We present here a crucial role for Hippo-Yap/Taz signaling in this context. Analysis of sav1 mutant zebrafish revealed dysplastic morphology and expansion of both intrahepatic and extrahepatic biliary cells, and ultimately larval lethality. Biliary dysgenesis, but not larval lethality, is driven primarily by Yap signaling. Re-expression of Sav1 protein in sav1-/- hepatocytes is able to overcome these initial deficits and allows sav1-/- fish to survive, suggesting cell non-autonomous signaling from hepatocytes. Examination of sav1-/- rescued adults reveals loss of gallbladder and formation of dysplastic cell masses expressing biliary markers, suggesting roles for Hippo signaling in extrahepatic biliary carcinomas. Deletion of stk3 revealed that the phenotypes observed in sav1 mutant fish function primarily through canonical Hippo signaling and supports a role for phosphatase PP2A, but also suggests Sav1 has functions in addition to facilitating Stk3 activity. Overall, this study defines a role for Hippo-Yap signaling in the maintenance of both intra- and extrahepatic biliary ducts.

A novel classification of aberrant right hepatic ducts ensures a critical view of safety in laparoscopic cholecystectomy.

BACKGROUND: Based on the spatial relationship of an aberrant right hepatic duct (ARHD) with the cystic duct and gallbladder neck, we propose a practical classification to evaluate the specific form predisposing to injury in laparoscopic cholecystectomy (LC). METHODS: We retrospectively investigated the preoperative images (mostly magnetic resonance cholangiopancreatography) and clinical outcomes of 721 consecutive patients who underwent LC at our institute from 2015 to 2018. We defined the high-risk ARHD as follows: Type A: communicating with the cystic duct and Type B: running along the gallbladder neck or adjacent to the infundibulum (the minimal distance from the ARHD < 5 mm), regardless of the confluence pattern in the biliary tree. Other ARHDs were considered to be of low risk. RESULTS: A high-risk ARHD was identified in 16 cases (2.2%): four (0.6%) with Type A anatomy and 12 (1.7%) with Type B. The remaining ARHD cases (n = 34, 4.7%) were categorized as low risk. There were no significant differences in the operative outcomes (operative time, blood loss, hospital stay) between the high- and low- risk groups. Subtotal cholecystectomy was applied in four cases (25%) in the high-risk group, a significantly higher percentage than the low-risk group (n = 1, 2.9%). In all patients with high-risk ARHD, LC was completed safely without bile duct injury or conversion to laparotomy. CONCLUSIONS: Our simple classification of high-risk ARHD can highlight the variants located close to the dissecting site to achieve a critical view of safety and may contribute to avoiding inadvertent damage of an ARHD in LC.

Ventral Portal Vein Over Gallbladder and Pancreas---An Exceptional Anatomical Variation Found in a Liver Transplant Patient: A Case Report.

BACKGROUND: Anatomic variations are well known in the liver hilum. A rare precholecystic, preduodenal, prepancreatic portal vein is described as found in a liver transplant candidate. Precholecystic location of portal vein is an exceptional finding and does not seem to have been previously described. It is associated with a preduodenal portal vein. Its position is challenging, as its surface can be mistaken with the gallbladder wall. We present the case of a patient candidate to liver transplantation. In the preoperative studies, a portal thrombosis was suspected, with recanalization by collaterals, but also a malformation was suggested. The patient had a primary biliary cirrhosis. Other findings included agenesis of inferior vena cava on the right side. During operation, the portal vein was found over the gallbladder and fixed to it, making it at first difficult to distinguish one from the other. CONCLUSIONS: A precholecystic portal vein is a rare finding that poses a challenge for the surgeon. It must be ruled out in the preoperative workout.

Immunohistochemical characteristics of ganglionated plexuses in the human gallbladder

Indirect triple immunolabelling techniques were used to identify the presence of choline acetyl-transferase (ChAT), neuronal nitric oxide synthase (nNOS), Dopamine beta-hydroxylase (DβH), neuromedin U-8 (NMU-8), and neuropeptide Y (NPY) in the ganglionated plexuses of the human gallbladder. Of all the intrinsic cholinergic neurons examined, NMU-8-immunoreactive (-IR) neurons appeared to be the most populous, followed closely by neurons containing NPY-IR. nNOS-IR neurons were often observed to coexist with ChAT, NMU, and NPY. Occasionally, these nNOS positive neurons were seen triple labeled with ChAT, NMU-8, and NPY. Results also indicate that not all nNOS and NMU-8-IR coexistent neurons express NPY immunoposi-tivity. Our findings suggest that these intrinsic neurons may be categorized into a distinct population of neurons that express both inhibitory and excita-tory capabilities.Intrinsic cholinergic neurons that were ChAT-IR displayed a spectrum of immunopositivity. Interestingly, a small subpopulation of these neurons ap-peared to be extremely weak ChAT-IR or simply ChAT-immunonegative. These occasionally obser-ved ChAT-immunonegative neurons at times ex-pressed single immunopositivity for NMU-8 or nNOS, while more frequently, these ChAT-immunonegative neurons were found to be single immunopositive, or at times, double immunopositi-ve for NMU-8-, NPY-, or nNOS-IR.Dopamine beta-hydroxylase (DβH) antibodies were used to confirm the lack of intrinsic sympat-hetic innervation in the human gallbladder. As suspected, in all the sections examined, DβH-IR neu-rons were not detected. The only indication of DβH immunopositivity was noted among delicate fibers surrounding the neurons and blood vessels within the organ

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Clinical anatomy of the anterior and posterior hepatic plexuses, including relations with the pancreatic plexus: A cadaver study.

The poor prognosis after surgery for pancreatic cancer or extrahepatic bile duct cancer has mainly been attributed to early lymph node metastasis, as well as a high frequency of perineural invasion along the peripancreatic neural plexuses or extrahepatic bile duct plexus. However, there has been no detailed morphological description of the anterior and posterior hepatic plexuses (AHP and PHP). In addition, the concepts of the pancreatic plexus and PHP are confused by surgeons. To assess the relations of the pancreatic plexus and hepatic plexuses from the morphological, developmental, and clinical perspectives, these plexuses were dissected in 24 cadavers. The PHP was found to be completely independent of the AHP. The PHP ran behind the portal vein, with most nerve fibers ascending along the bile duct to the gallbladder and the liver or descending to the distal common bile duct and duodenal papilla. Some branches of the PHP contributed to the pancreatic plexus, corresponding to pancreatic head plexus I as defined by the Japan Pancreas Society. The differences between the PHP and pancreatic head plexus I should be understood, even though liver function is not obviously affected after PHP excision for pancreatic head cancer. Further study is needed to determine whether there are functional differences between the AHP and PHP. Clin. Anat., 33:630-636, 2020. © 2019 Wiley Periodicals, Inc.

Prevalence of anatomic landmarks for orientation during elective laparoscopic cholecystectomies.

BACKGROUND: We sought to determine the prevalence of common anatomic landmarks around the gallbladder that may be useful in orienting surgeons during laparoscopic cholecystectomy. METHODS: The subhepatic anatomy of 128 patients undergoing elective cholecystectomy was recorded. We searched and recorded the presence of five anatomic landmarks: the bile duct (B), the Sulcus of Rouviere (S), the left hepatic artery (A), the umbilical fissure (F), and the duodenum (E). These are the previously described B-SAFE landmarks. RESULTS: We found that the duodenum and umbilical fissure were present reliably in almost all patients. The position of the left hepatic artery could be reliably determined by its pulsation in 84% of patients. A portion of the bile duct could be seen in 77% and the Sulcus of Rouviere was present in 80%. Furthermore, the hepatobiliary triangle was always found superior or at the same level as the Sulcus of Rouviere. CONCLUSIONS: We found that these five anatomic landmarks were reliably present. This suggest that using the B-SAFE landmarks may allow a surgeon to more easily orient before and during laparoscopic cholecystectomy and prevent bile duct injuries.

Ultrasound findings in paediatric cholestasis: how to image the patient and what to look for.

Paediatric biliary tract and gallbladder diseases include a variety of entities with a wide range of clinical presentations. Cholestasis represents an impaired secretion of bilirubin by hepatocytes, manifesting with high blood levels of conjugated bilirubin and jaundice. Various causes may be involved, which can be recognised analysing blood tests and hepatobiliary imaging, while sometimes liver biopsy or surgery may be necessary. High-resolution real-time ultrasonography is an important tool for differentiation of obstructive and non-obstructive causes of jaundice in infants and children. In this paper, we briefly review the normal anatomy and the ultrasound aspects of main pathologies affecting gallbladder and biliary tree in neonatal and paediatric age.

Gallbladder and Biliary Disease in Pregnancy.

Diseases of the gallbladder and biliary tract are extremely common in developed nations. Because of the physiology of pregnancy, their incidence increases during gestation. This article represents a review of the existing literature on the entire spectrum of biliary disease. The physiology, clinical presentation, and diagnostic evaluation of a variety of conditions are reviewed. Historical and contemporary data regarding pregnancy implications and treatment options are discussed.

Gallbladder contraction at CT and sonography secondary to bowel preparation for colonoscopy.

PURPOSE: To investigate volume changes of the gallbladder at computed tomography (CT) following bowel preparation for colonoscopy and to evaluate the incidence of gallbladder contraction at abdominal sonography performed with colonoscopy on the same day. METHODS: During a 1-year period, 222 patients underwent abdominal CT (CT1) and colonoscopy on the same day. Among them, 123 patients had prior CT imaging without receiving colonoscopy in the past were enrolled. Manual estimates of 3D gallbladder volume were obtained from two CT scans to evaluate whether gallbladder volume changed as a result of bowel preparation for colonoscopy. During the same 1-year period, another 89 patients underwent abdominal sonography and colonoscopy on the same day (sonography group). The short-axis diameters of the gallbladder on the longitudinal scan of sonography from these patients were obtained. RESULTS: Gallbladder volume was significantly larger on prior CT without colonoscopy (31.7 ± 15.4 cm3) than on CT1 (20.3 ± 11.1 cm3) (p < 0.001). Gallbladder volume decreased by more than 50% in 41 of 123 patients (33%) who underwent abdominal CT and colonoscopy on the same day, compared with standard CT. In the sonography group (n = 89), the short-axis diameters of the gallbladder were less than 1.5 cm in 41 patients (46%) and less than 1.0 cm in 17 patients (19%). CONCLUSION: Contracted gallbladder secondary to bowel preparation can be seen on imaging when performed with same-day colonoscopy. Such a situation may lead to the incomplete or inadequate evaluation of the gallbladder on imaging with same-day colonoscopy.

Developmental milestones in neonatal and juvenile C57Bl/6 mouse - Indications for the design of juvenile toxicity studies.

There is a growing demand for wild type mice and mouse models of disease that may be more representative of human conditions but there is little information on neonatal and juvenile mouse anatomy. This project produces sound and comprehensive histology background data on the developing neonatal mouse at different time points from Day 0 until Day 28. The work describes optimal methods for tissue harvesting, fixation and processing from the neonatal and juvenile mice which can be used in routine toxicology studies. A review of the available literature revealed inconsistencies in the developmental milestones reported in the mouse. Although it is true that the sequence of events during the development is virtually the same in mice and rats, important developmental milestones in the mouse often happen earlier than in the rat, and these species should not be used interchangeably.

Anatomy of rodent and human livers: What are the differences?

The size of the liver of terrestrial mammals obeys the allometric scaling law over a weight range of >3 ∗ 106. Since scaling reflects adaptive changes in size or scale among otherwise similar animals, we can expect to observe more similarities than differences between rodent and human livers. Obvious differences, such as the presence (rodents) or absence (humans) of lobation and the presence (mice, humans) or absence (rats) of a gallbladder, suggest qualitative differences between the livers of these species. After review, however, we conclude that these dissimilarities represent relatively small quantitative differences. The microarchitecture of the liver is very similar among mammalian species and best represented by the lobular concept, with the biggest difference present in the degree of connective tissue development in the portal tracts. Although larger mammals have larger lobules, increasing size of the liver is mainly accomplished by increasing the number of lobules. The increasing role of the hepatic artery in lobular perfusion of larger species is, perhaps, the most important and least known difference between small and large livers, because it profoundly affects not only interventions like liver transplantations, but also calculations of liver function.

Secondary Imaging Findings Aid in Prenatal Diagnosis and Characterization of Congenital Diaphragmatic Hernia: Role of an Abnormal Orientation of Vascular Structures and Gallbladder Position.

OBJECTIVES: To determine whether an abnormal orientation of the abdominal or hepatic vasculature and an abnormal gallbladder position on prenatal ultrasound (US) imaging are associated with intrathoracic liver herniation and postnatal outcomes in cases of congenital diaphragmatic hernia (CDH). METHODS: Children who underwent prenatal US examinations and postnatal CDH repair at our institution were eligible. Prenatal US images were reviewed, and the orientation of the superior mesenteric artery (SMA) and hepatic veins as well as gallbladder position were recorded. Findings were correlated with prenatal US measurements (lung-to-head ratio and calculated observed-to-expected lung-to-head ratio) and postnatal outcomes, including intrathoracic liver herniation, an extracorporeal membrane oxygenation (ECMO) requirement, and mortality. RESULTS: A total of 175 patients met inclusion criteria. The SMA was shown in 168 cases and had a cephalad orientation in 95.4% (161 of 168), which was not associated with outcome measures and represented bowel herniation. A cephalad orientation of the hepatic veins was identified in 52.6% (90 of 171) and was associated with intrathoracic liver herniation, an ECMO requirement, and mortality (P < .01). In right-sided CDH, the gallbladder was intrathoracic in 91.3% (21 of 23). In left-sided CDH, an abnormal gallbladder position was seen in 51.3% (76/152) and was associated with intrathoracic liver herniation, an ECMO requirement, mortality, and lower lung-to-head ratio and observed-to-expected lung-to-head ratio values. When combined, abnormal hepatic vein and gallbladder positions showed good sensitivity and specificity in predicting intrathoracic liver herniation (area under the curve, 0.93). CONCLUSIONS: Abnormal SMA, hepatic vein, and gallbladder positions can be used to improve prenatal characterization of CDH. Accurate depiction of these structures on prenatal US images may aid in patient counseling and postnatal management.

Biliary tract in trident, an anatomical variation between the cystic duct and its union to the common hepatic duct: a rare case report / Tracto biliar en tridente, una variación anatómica entre el conducto cístico y su unión al conducto hepático común: un caso raro

SUMMARY: Given that the gallbladder and the biliary tract are subject to multiple anatomical variants, detailed knowledge of embryology and its anatomical variants is essential for the recognition of the surgical field when the gallbladder is removed laparoscopically or by laparotomy, even when radiology procedures are performed. During a necropsy procedure, when performing the dissection of the bile duct is a rare anatomical variant of the bile duct, in this case the cystic duct joins at the confluence of the right and left hepatic ducts giving an appearance of trident. This rare anatomical variant in the formation of common bile duct is found during the exploration of the bile duct during a necropsy procedure, it is clear that the wrong ligation of a common hepatic duct can cause a great morbi-mortality in the postsurgical of biliary surgery. This rare anatomical variant not previously described is put in consideration to the scientific community. Anatomical variants of the biliary tract are associated with high rates of morbidity and mortality, causing serious bile duct injuries. Only the surgical skill of the surgeon and his open mind to the possibilities of abnormalities make the performance of cholecystectomy a safe procedure.

RESUMEN: Dado que la vesícula biliar y el tracto biliar están sujetos a múltiples variantes anatómicas, el conocimiento detallado de la embriología y sus variantes anatómicas es esencial para el reconocimiento del campo quirúrgico cuando la vesícula biliar se extirpa laparoscópicamente o por laparotomía, incluso cuando se realizan procedimientos de radiología. Durante un procedimiento de necropsia, se realiza la disección del conducto biliar y se observa una variante anatómica inusual del conducto biliar; en este caso, el conducto cístico se une a la confluencia de los conductos hepáticos derecho e izquierdo dando una apariencia de tridente. Esta rara variante anatómica en la formación del conducto biliar común puede causar una gran morbimortalidad en la cirugía biliar asociado a una ligadura incorrecta. Esta extraña variante anatómica no descrita anteriormente se reporta a la comunidad científica, debido a que las variantes anatómicas del tracto biliar se asocian con altas tasas de morbilidad y mortalidad, al causar lesiones graves en el conducto biliar. Solo la habilidad quirúrgica del cirujano y su mente abierta a las posibilidades de variaciones anatómicas hacen que la realización de la colecistectomía sea un procedimiento seguro.

Contrast-enhanced ultrasound examination of the gallbladder and bile ducts: A pictorial essay.

The gallbladder and bile ducts are usually assessed initially with conventional gray-scale ultrasound (US). Contrast enhanced US (CEUS) is used when a diagnosis cannot be reached with conventional US. CEUS is easy to learn and perform. US contrast agents can be safely administered in patients with renal function impairment. In this pictorial essay the physics, examination technique and indications of CEUS for examining the gallbladder and bile ducts are reviewed. Gallbladder indications include elucidating normal variants, differentiating sludge from neoplastic lesions, benign and malignant pathology, infection, wall rupture and hemobilia. In the biliary tree CEUS is used for studying benign and malignant tumors, including metastases and cholangiocarcinoma, as well as intrabiliary injection.

One duct, two orifices, no names! the anatomy of the biliary cystic duct.

The biliary cystic duct (CD) connects the gallbladder to the extra-hepatic bile duct, and the point at which it does this delineates the division between the common hepatic duct and the common bile duct. Its clinical relevance in disease, and importance during interventions relating to the gallbladder mean that its normal and variant anatomy has been described extensively in literature. However, an aspect not yet fully described includes naming of its two orifices on either end. This is highly relevant for surgical, endoscopic, and percutaneous procedures. We describe these as encountered in normal CD and biliary tree anatomy. We believe this is crucial for interventions relating to the gallbladder and the biliary tree, including prevention of iatrogenic injury. Clin. Anat. 31:422-423, 2018. © 2018 Wiley Periodicals, Inc.

Anatomy and development of the extrahepatic biliary system in mouse and rat: a perspective on the evolutionary loss of the gallbladder.

The gallbladder is the hepatobiliary organ for storing and secreting bile fluid, and is a synapomorphy of extant vertebrates. However, this organ has been frequently lost in several lineages of birds and mammals, including rodents. Although it is known as the traditional problem, the differences in development between animals with and without gallbladders are not well understood. To address this research gap, we compared the anatomy and development of the hepatobiliary systems in mice (gallbladder is present) and rats (gallbladder is absent). Anatomically, almost all parts of the hepatobiliary system of rats are topographically the same as those of mice, but rats have lost the gallbladder and cystic duct completely. During morphogenesis, the gallbladder-cystic duct domain (Gb-Cd domain) and its primordium, the biliary bud, do not develop in the rat. In the early stages, SOX17, a master regulator of gallbladder formation, is positive in the murine biliary bud epithelium, as seen in other vertebrates with a gallbladder, but there is no SOX17-positive domain in the rat hepatobiliary primordia. These findings suggest that the evolutionary loss of the Gb-Cd domain should be translated simply as the absence of a biliary bud at an early stage, which may correlate with alterations in regulatory genes, such as Sox17, in the rat. A SOX17-positive biliary bud is clearly definable as a developmental module that may be involved in the frequent loss of gallbladder in mammals.