Mechanism of primitive duct formation in the pancreas and submandibular glands: a role for SDF-1

BACKGROUND: The exocrine pancreas is composed of a branched network of ducts connected to acini. They are lined by a monolayered epithelium that derives from the endoderm and is surrounded by mesoderm-derived mesenchyme. The morphogenic mechanisms by which the ductal network is established as well as the signaling pathways involved in this process are poorly understood. RESULTS: By morphological analyzis of wild-type and mutant mouse embryos and using cultured embryonic explants we investigated how epithelial morphogenesis takes place and is regulated by chemokine signaling. Pancreas ontogenesis displayed a sequence of two opposite epithelial transitions. During the first transition, the monolayered and polarized endodermal cells give rise to tissue buds composed of a mass of non polarized epithelial cells. During the second transition the buds reorganize into branched and polarized epithelial monolayers that further differentiate into tubulo-acinar glands. We found that the second epithelial transition is controlled by the chemokine Stromal cell-Derived Factor (SDF)-1. The latter is expressed by the mesenchyme, whereas its receptor CXCR4 is expressed by the epithelium. Reorganization of cultured pancreatic buds into monolayered epithelia was blocked in the presence of AMD3100, a SDF-1 antagonist. Analyzis of sdf1 and cxcr4 knockout embryos at the stage of the second epithelial transition revealed transient defective morphogenesis of the ventral and dorsal pancreas. Reorganization of a globular mass of epithelial cells in polarized monolayers is also observed during submandibular glands development. We found that SDF-1 and CXCR4 are expressed in this organ and that AMD3100 treatment of submandibular gland explants blocks its branching morphogenesis. CONCLUSION: In conclusion, our data show that the primitive pancreatic ductal network, which is lined by a monolayered and polarized epithelium, forms by remodeling of a globular mass of non polarized epithelial cells. Our data also suggest that SDF-1 controls the branching morphogenesis of several exocrine tissues.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

La expresión oral en euskara del alumnado de bachillerato del modelo D en Navarra

La expresión oral es una de las habilidades lingüísticas principales en la producción de una lengua y el índice de progreso y dominio en el aprendizaje de la segunda lengua (L2). La expresión oral de los aprendices de la L2 está caracterizada por una sucesión de estadios que cada aprendiz atraviesa hasta la competencia oral en esa lengua. Este artículo estudia la expresión oral en euskara de los alumnos del modelo lingüístico D de Navarra al finalizar sus estudios de 1º de bachillerato. Estos alumnos de lengua materna euskera, español o ambas han seguido sus estudios en lengua vasca en las diferentes etapas educativas. En concreto se trata de analizar la calidad idiomática de los alumnos en la prueba de expresión oral perteneciente al examen certificativo del ciclo superior de euskara, llevado a cabo por la Escuela Oficial de Idiomas a Distancia de Navarra. La frecuencia y distribución de los errores en la producción oral se han correlacionado con la zona lingüística de procedencia de los centros educativos. Los resultados ponen de relieve la necesidad de incluir dentro del currículo un programa transversal orientado hacia el uso formal de la lengua hablada.Mintzamena hizkuntzaren ekoizpenak duen trebetasunik garrantzitsuenetakoa da eta bigarren hizkuntzaren (L2) ikaskuntzan aurrerapenaren eta gaitasunaren adierazle. Ikastunek hizkuntza horretan ahozko gaitasuna lortu arte gainditu behar duten estadio-segida L2-ko ikastunen mintzamenaren ezaugarria da. Artikulu honek Nafarroako D hizkuntz-ereduan dauden Batxilergoko 1. mailako ikasleen mintzamena, euskaran, aztertu du. Ikasle hauek, ama hizkuntza euskara, gaztelera edo biak dituztenak, euskaraz egin dituzte beraien ikaskuntzak hezkuntza-etapa ezberdinetan. Zehazki, Nafarroako Urrutiko Hizkuntza Eskola Ofizialean egindako Goi Zikloko azterketaren ahozko proban, ikasleek adierazi duten hizkuntza kalitatea aztertzean datza. Ahozko ekoizpenean egin diren akatsen maiztasuna eta sailkapena eta ikastetxeen jatorrizko hizkuntz-eremua korrelazioan jarri dira. Emaitzek kurrikuluan ahozko hizkuntzaren erabilera formala lantzera zuzendutako zehar-programa sar - tzeko beharra nabarmendu dute.Oral expression is one of the main language skills in the production of a language and the indicators of progress and command when learning a second language (L2). The oral expression of L2 learners is characterised by a succession of stages which each student passes before reaching oral competence in the language. This article studies the oral expression in Basque of students studying in Navarre’s language model D on finishing their 1st year of “ba - chillerato” (High school). These students, whose mother tongue is either Basque or Castilian or both, have studied in the Basque language throughout the different stages of their formal education. More specifically, the aim is to analyse the language quality of students in the oral expression test which forms part of the examination certifying the superior study level in Basque set by the Official Navarrese Distance-learning Language School. The frequency and distribution of mistakes in oral production were correlated to the language area the education centres were based in. The results highlight the need to include a cross-curricular programme aimed at the formal use of the language in the curriculum

Tumor classification and selection of tumor areas with high density of <i>CK7</i>+ cells.

<p><b>(A-C)</b> Tumors were classified as well-, moderately- and poorly-differentiated. <b>(D-F)</b> Immunohistochemical detection of <i>CK7</i> in representative histologically-graded ICCs. Areas with at least 50% of <i>CK7</i> staining were selected for further RNA extraction and immunofluorescence stainings. White scale bars = 200 μm. Black scale bars = 500 μm</p

Selection of microRNAs associated with ICC differentiation grade.

<p>Selection of microRNAs associated with ICC differentiation grade.</p

Biliary-specific proteins are not differentially expressed among histologically-graded ICC's.

<p><b>(A)</b> All markers are expressed (qRT-PCR) at lower levels in ICC as compared to distant non-tumoral tissue. (Mean ± SEM; *p<0.05, **p<0.01, ***p<0.001). <b>(B-C)</b> Lack of correlation between molecular differentiation marker expression and tumor grade when comparing <b>(B)</b> ICC samples or <b>(C)</b> the ratio of expression in tumor versus non-tumor tissue. Dots represent individual ICC samples and horizontal bars represent mean of the samples.</p