Many morphogenetic movements during development require the formation of transient intermediates called rosettes. Within rosettes, cells are polarized with apical ends constricted towards the rosette center and nuclei basally displaced. Whereas the polarity and cytoskeletal machinery establishing these structures has been extensively studied, the extracellular cues and intracellular signaling c...

Embryonic development requires a complex series of relative cellular movements and shape changes that are generally referred to as morphogenesis. Although some of the mechanisms underlying morphogenesis have been identified, the process is still poorly understood. Here, we address mechanisms of epithelial morphogenesis using the vertebrate lens as a model system. We show that the apical constri...

Rho family GTPases regulate many morphogenetic processes during vertebrate development including neural tube closure. Here we report a function for GEF-H1/Lfc/ArhGEF2, a RhoA-specific guanine nucleotide exchange factor that functions in neurulation in Xenopus embryos. Morpholino-mediated depletion of GEF-H1 resulted in severe neural tube defects, which were rescued by GEF-H1 RNA. Lineage tracin...

background: root morphology is of utmost importance to endodontic sciences. since there are a few studies on the morphology of mandibular second molars’ roots, and some anatomical variables are not evaluated before, the aim of this study was to investigate thoroughly radicular anatomy of this tooth. materials and methods: this ex vivo study was performed on 150 intact mandibular second molars. ...

BACKGROUND The purpose of this study was to compare the shaping ability of the ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (WO; Dentsply Maillefer) and ProTaper Next (PTN; Dentsply Maillefer) in simulated L-shaped and S-shaped root canals respectively. METHODS 30 simulated L-shaped and 30 simulated S-shaped root canals in resin blocks were employed and rando...

October 2003 ORAL HEALTH 75 T he ‘Apical Control Zone’ is a matrix-like region created in the apical third of the root canal space. The zone demonstrates an exaggerated taper from the clinician defined apical constriction whether this is spatially a linear or point determination. This enhanced taper in the apical control zone provides resistance form against the condensation pressures of obtura...

Cell constriction promotes epithelial sheet invagination during embryogenesis across phyla. However, how this cell response is linked to global patterning information during organogenesis remains unclear. To address this issue, we have used the Drosophila eye and studied the formation of the morphogenetic furrow (MF), which is characterized by cells undergoing a synchronous apical constriction ...