We labeled axonal projections using carbocyanine dyes in the developing rat brain to study cellular interactions that might underlie establishment of thalamocortical connectivity. By embryonic day 14 (E14), groups neurons ventral diencephalon and primitive internal capsule have established dorsal thalamus, thalamic fibers pass topographic order among them. Simultaneously, axons from early-born cells both subplate marginal zone (i.e., original cortical preplate) establish an ordered array...

Fluctuations in the shape of amnioserosa (AS) cells during Drosophila dorsal closure (DC) provide an ideal system with which to understand contractile epithelia, both terms cellular mechanisms and how tissue behaviour emerges from activity individual cells. Using quantitative image analysis we show that apical fluctuations are driven by medial cytoskeleton, periodic foci myosin actin travelling across cell apices. Shape changes were mostly anisotropic neighbouring often, but transiently,...

ABSTRACT We have taken advantage of the optical transparency zebrafish embryos to investigate patterns cell division, movement and shape during early stages development central nervous system. The surface-most epiblast cells gastrula neurula stage were imaged analysed using a computer-based, time-lapse acquisition system attached differential interference contrast (DIC) microscope. find that onset gastrulation is accompanied by major changes in behaviour. Cells collect into cohesive sheet,...

Promptly after the notochord domain is specified in vertebrate dorsal mesoderm, it undergoes dramatic morphogenesis. Beginning during gastrulation,convergence and extension movements change a squat cellular array into narrow, elongated one that defines primary axis of embryo. Convergence might be coupled by highly organized intermixing known as mediolateral intercalation behavior (MIB). To learn whether MIB drives early morphogenesis zebrafish notochord, we made 4D recordings quantitatively...

The cellular mechanisms underlying organ formation are largely unknown. We visualized early vertebrate eye morphogenesis at single-cell resolution by in vivo imaging medaka (Oryzias latipes). Before optic vesicle evagination, retinal progenitor cells (RPCs) modulate their convergence a fate-specific manner. Presumptive forebrain converge toward the midline, whereas medial RPCs remain stationary, predetermining site of evagination. Subsequent evagination is driven active migration individual...

How genetic programs generate cell-intrinsic forces to shape embryos is actively studied, but less so how tissue-scale physical impact morphogenesis. Here we address the role of latter during axis extension, using Drosophila germband extension (GBE) as a model. We found previously that cells elongate in anteroposterior (AP) extending germband, suggesting an extrinsic tensile force contributed body extension. further characterized AP cell elongation patterns GBE, by tracking and quantifying...

Halfway through embryonic development, the epidermis of Drosophila exhibits a gap at dorsal side covered by an extraembryonic epithelium, amnioserosa (AS). Dorsal closure (DC) is process whereby interactions between two epithelia establish epidermal continuity. Although genetic and biomechanical analysis have identified AS as force-generating tissue, we do not know how individual cell behaviours are transformed into tissue movements. To approach this question applied novel image-analysis...

Convergence and extension movements elongate tissues during development. Drosophila germ-band (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. Here, we develop novel computational methods to analyse the spatiotemporal dynamics of GBE, at scale tissue. We show that initial bipolar polarization gives way unipolar enrichment parasegmental boundaries two further within each parasegment, concomitant with a doubling number as tissue...

Highlights•Large-scale rearrangement of microtubules accompanies early tube formation•Loss leads to loss apical constriction during formation•During tubulogenesis, is driven by pulsatile medial actomyosin•Microtubules and the cytolinker Shot stabilize actomyosinSummaryThe cytoskeleton a major determinant cell-shape changes that drive formation complex tissues development. Important roles for actomyosin tissue morphogenesis have been identified, but role microtubule less clear. Here, we show...

During vertebrate gastrulation, highly coordinated cellular rearrangements lead to the formation of three germ layers, ectoderm, mesoderm and endoderm. In zebrafish, silberblick (slb)/wnt11regulates normal gastrulation movements by activating a signalling pathway similar Frizzled-signalling pathway, which establishes epithelial planar cell polarity (PCP) in Drosophila. However, mechanisms slb/wnt11 functions during zebrafish are still unclear. Using high-resolution two-photon confocal...

Cospeciation generally increases the similarity between host and parasite phylogenies. Incongruence phylogenies has previously been explained in terms of switching, sorting, duplication events. Here, we describe an additional process, failure to speciate response speciation, that may be important some host-parasite systems. Failure is likely occur when gene flow among populations much higher than their hosts. We reconstructed trees from mitochondrial nuclear DNA sequences for pigeons doves...

Abstract Some species of parasites occur on a wide range hosts while others are restricted to one or few host species. The specificity parasite is determined, in part, by its ability disperse between Dispersal limitations can be studied exploring the genetic structure populations both within single and across multiple In this study we examined mitochondrial cytochrome oxidase I (COI) gene two genera lice (Insecta: Phthiraptera) occurring sympatric doves southern North Central America. One...

In the mutant mouse reeler , tangential distribution of thalamocortical fibers is essentially normal, even though neurons cortical plate accumulate below entire early-born preplate population (Caviness et al., 1988). This seems incompatible with hypothesis that cells subplate (the lower component in normal mammals) form an axonal scaffold guides thalamic and act as temporary targets for them (Blakemore Molnár, 1990, Shatz 1990). We used carbocyanine dyes to trace projections wild-type mice...

Mechanisms for shaping and folding sheets of cells during development are poorly understood. An example is the complex reorganisation forebrain neural plate neurulation, which must fold a sheet into tube while evaginating two eyes from single contiguous domain within plate. We, first time, track these cell rearrangements to show that morphogenesis differs significantly prior hypotheses. We postulate new model neurulation demonstrate how mutations affecting signalling pathways can generate...