During gastrulation in Drosophila melanogaster, coordinated apical constriction of the cellular surface drives invagination of the mesoderm anlage. Forces generated by the cortical cytoskeletal network have a pivotal role in this cellular shape change. Here, we show that the organisation of cortical actin is essential for stabilisation of the cellular surface against contraction. We found that ...

OBJECTIVE The purpose of this in vivo study was to compare the ability of digital tactile, digital radiographic and electronic methods to determine reliability in locating the apical constriction. MATERIALS AND METHODS Informed consent was obtained from patients scheduled for orthodontic extraction. The teeth were anesthetized, isolated and accessed. The canals were negotiated, pulp chamber a...

We use laser hole drilling to assess the mechanics of an embryonic epithelium during development-in vivo and with subcellular resolution. We ablate a subcellular cylindrical hole clean through the epithelium and track the subsequent recoil of adjacent cells (on ms time scales). We investigate dorsal closure in the fruit fly with emphasis on apical constriction of amnioserosa cells. The mechanic...

The requirements of a spherical reference system based on two orthogonal goniometers show a surprising correspondence with the evidence emerging from numerous experimental studies on centrioles and centrosomes: the centrosome, because of the 9-fold symmetry of its centrioles, their orthogonal arrangement and their circumferential polarity, may play the role of an interface, composed by two orth...

INTRODUCTION Accurate determination of working length (WL) is a critical factor for endodontic success. This is commonly achieved using an apex locator which is influenced by the presence or absence of the apical constriction. Hence, this study was done to compare the accuracy of two generations of apex locators in teeth with simulated apical root resorption. MATERIALS AND METHODS Forty maxil...

The process of epithelial morphogenesis is ubiquitous in animal development, but much remains to be learned about the mechanisms that shape epithelial tissues. The follicle cell (FC) epithelium encapsulating the growing germline of Drosophila is an excellent system to study fundamental elements of epithelial development. During stages 8 to 10 of oogenesis, the FC epithelium transitions between ...

Many epithelial tissues undergo extensive remodelling during morphogenesis. How their epithelial features, such as apicobasal polarity or adhesion, are maintained and remodelled and how adhesion and polarity proteins contribute to morphogenesis are two important questions in development. Here, we approach these issues by investigating the role of the apical determinant protein Crumbs (Crb) duri...

AIM To evaluate the effects of a preflaring method on the determination of working length in the curved mesial canals of mandibular molars. MATERIALS AND METHODS Ninety mandibular molars with apical curvature of 30 to 40° were selected and randomly divided into two groups; each containing 45 teeth. In the first group, the initial instrumentation was performed with preflaring on the mesiobucca...