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Specialised subapical junctions play a critical role in maintaining epithelial cell polarity and tissue integrity, and provide a platform for intracellular signalling. Here we analyse the roles of C. elegans genes let-413 and dlg-1, a homologue of Drosophila lethal discs large, in the assembly of the C. elegans apical junction (CeAJ), and provide the first(More)
Glial cells constitute the second component of the nervous system and are important during neuronal development. In this paper we describe a gene, glial cell deficient, (glide), that is necessary for glial cell fate commitment in Drosophila melanogaster. Mutations at the glide locus prevent glial cell determination in the embryonic central and peripheral(More)
A null mutation was generated in the mouse RXR alpha gene by targeted disruption. Growth deficiency occurred in heterozygote mice. Null mutants died in utero and displayed myocardial and ocular malformations. These malformations belong to the fetal vitamin A deficiency syndrome, supporting the idea that RXR alpha is involved in retinoid signaling in vivo. A(More)
First lower E-14 and E-16 mouse molars and E-13 lower incisors were cultured in vitro and either sequentially or continuously labelled with BrdU (5-bromo-2'-deoxyuridine). The behaviour of the non-cycling inner dental epithelial cells emerging from the enamel knot area of the molars was analysed by 3D (three dimensional) reconstructions of serial sections.(More)
Mutation in the CSB gene results in the human Cockayne's syndrome (CS). Here, we provide evidence that CSB is found not only in the nucleoplasm but also in the nucleolus within a complex (CSB IP/150) that contains RNA pol I, TFIIH, and XPG and promotes efficient rRNA synthesis. CSB is active in in vitro RNA pol I transcription and restores rRNA synthesis(More)
This study provides a detailed description of the anatomical defects in the Hoxa-1-/- mutant mice previously generated in our laboratory (T. Lufkin, A. Dierich, M. LeMeur, M. Mark and P. Chambon, 1991; Cell 66, 1105-1119). Three-dimensional reconstructions of the Hoxa-1-/- rhombencephalon reveals that it bears only five rhombomeric structures (ie.(More)
Tooth morphogenesis is a complex multifactorial process in which differential mitotic activities and cell death play important roles. Upper first (m1) and second (m2) molars from mouse embryos were investigated from early cap to bell stage. m2 differed from m1 by delayed origin of the enamel grooves delimiting the protrusion of the cap bottom towards the(More)
The development of the lower incisor in the mouse was investigated from histological sections using computer-aided 3D reconstructions. At ED 13.0, the incisor was still at the bud stage. At ED 13.5, the initial cap was delimited by a short cervical loop, the development of which proceeded on the labial side, but was largely retarded on the medial side. This(More)
The enamel knot (EK), located in the center of cap-stage tooth germs, is a transitory cluster of non-dividing epithelial cells, eventually linked to the outer dental epithelium by the enamel septum (ES). It might act as a signaling center providing positional information for tooth morphogenesis and could regulate the growth of tooth cusps through the(More)
First lower molar development in the mouse was investigated from the cap to early bell stage using histology, morphometry, TEM and 3D reconstructions. This period was characterized by the histogenesis of the enamel organ (EO), folding of the epithelio-mesenchymal junction and growth of the tooth. The histogenesis of the EO and appearance of the enamel knot(More)