Topic
Mesoderm morphogenesis
About: Mesoderm morphogenesis is a research topic. Over the lifetime, 20 publications have been published within this topic receiving 635 citations.
Papers
TL;DR: It is proposed that the integration of Pyr and Ths function is required for robustness of Htl-dependent mesoderm spreading and differentiation, but that the functions of Pyr have become more specific, possibly representing an early stage of functional divergence after gene duplication of a common ancestor.
Abstract: Thisbe (Ths) and Pyramus (Pyr), two closely related Drosophila homologues of the vertebrate fibroblast growth factor (FGF) 8/17/18 subfamily, are ligands for the FGF receptor Heartless (Htl). Both ligands are required for mesoderm development, but their differential expression patterns suggest distinct functions during development. We generated single mutants and found that ths or pyr loss-of-function mutations are semi-lethal and mutants exhibit much weaker phenotypes as compared with loss of both ligands or htl. Thus, pyr and ths display partial redundancy in their requirement in embryogenesis and viability. Nevertheless, we find that pyr and ths single mutants display defects in gastrulation and mesoderm differentiation. We show that localised expression of pyr is required for normal cell protrusions and high levels of MAPK activation in migrating mesoderm cells. The results support the model that Pyr acts as an instructive cue for mesoderm migration during gastrulation. Consistent with this function, mutations in pyr affect the normal segmental number of cardioblasts. Furthermore, Pyr is essential for the specification of even-skipped-positive mesodermal precursors and Pyr and Ths are both required for the specification of a subset of somatic muscles. The results demonstrate both independent and overlapping functions of two FGF8 homologues in mesoderm morphogenesis and differentiation. We propose that the integration of Pyr and Ths function is required for robustness of Htl-dependent mesoderm spreading and differentiation, but that the functions of Pyr have become more specific, possibly representing an early stage of functional divergence after gene duplication of a common ancestor.
54 citations
TL;DR: Time-lapse videomicroscopy, scanning electron microscopy, histological sections and lineage tracers have shown that, in C. ornata, some prospective notochord, somite and tailbud mesoderm cells leave the surface epithelium of the archenteron by ingression.
Abstract: Ceratophrys ornata, the Argentinean horned frog, has a significantly different pattern of early morphogenesis than does the most studied amphibian, Xenopus laevis. Time-lapse videomicroscopy, scanning electron microscopy, histological sections and lineage tracers have shown that, in C. ornata, some prospective notochord, somite and tailbud mesoderm cells leave the surface epithelium of the archenteron by ingression. After gastrulation, SEM reveals cells with constricted apices and a bottle shape in three zones on the archenteron roof and in a fourth zone around the blastopore. Prospective somitic tissue ingresses first from two lateral zones, followed by ingression of prospective notochord from the medial zone and tailbud mesoderm from the circumblastoporal zone. This is unlike X. laevis, in which no cells with constricted apices are present on the dorsal surface of the archenteron, nor do any cells ingress into the deep mesodermal layers from the surface layer.
48 citations
TL;DR: This morphological analysis describes the similarity of gastrula structure in the sturgeon and the amphibian Xenopus laevis, and suggests that the species share many developmental mechanisms.
Abstract: This study presents a detailed description of gastrulation in the white sturgeon, Acipenser transmontanus, using scanning electron microscopy, histology, and time-lapse filming and video microscopy. This morphological analysis describes the similarity of gastrula structure in the sturgeon and the amphibian Xenopus laevis, and suggests that the species share many developmental mechanisms. It also identifies important differences, such as the equatorial dorsal lip in sturgeon, and provides a basis for interpreting experiments that test the effect of these differences on gastrulation. The onset of gastrulation in the sturgeon is marked by the appearance of a blastoporal equatorial pigment line that forms as the apices of bottle cells contract and concentrate surface pigment granules. Bottle cell formation at the blastopore lip and involution of surface material through the blastopore are strikingly similar to the equivalent processes in amphibian embryos. As gastrulation continues, a distinct cleft of Brachet forms between pre-involution and post-involution material. Following involution, the prospective axial mesoderm located on the dorsal surface of the late blastula (Ballard and Ginsburg: J. Exp. Zool., 213:69-103, 1980) ingresses from a central zone in the posterior archenteron roof surface in a process that is unlike any in Xenopus, but resembles events in other amphibians (Purcell, 1992; Smith: Dev. Biol., 98:250-254, 1983; King: Biol. Bull., 4:287-300, 1903). The detailed comparison of similarities and differences in gastrulation in different vertebrate lineages yields insights into the function and versatility of common developmental mechanisms.
47 citations
TL;DR: The dorsal mesoderm in the frog Hymenochirus forms by a mechanism not previously described in any other vertebrate, a novel morphogenetic process the authors dub "relamination."
45 citations
TL;DR: It is shown here that FGF plays multiple roles at successive stages of mesoderm morphogenesis in Drosophila, and it is shown that both movements are important for layer formation and present evidence suggesting that they are controlled by genetically distinct mechanisms.
Abstract: Fibroblast growth factor (FGF)-dependent epithelial-mesenchymal transitions and cell migration contribute to the establishment of germ layers in vertebrates and other animals, but a comprehensive demonstration of the cellular activities that FGF controls to mediate these events has not been provided for any system. The establishment of the Drosophila mesoderm layer from an epithelial primordium involves a transition to a mesenchymal state and the dispersal of cells away from the site of internalisation in a FGF-dependent fashion. We show here that FGF plays multiple roles at successive stages of mesoderm morphogenesis in Drosophila. It is first required for the mesoderm primordium to lose its epithelial polarity. An intimate, FGF-dependent contact is established and maintained between the germ layers through mesoderm cell protrusions. These protrusions extend deep into the underlying ectoderm epithelium and are associated with high levels of E-cadherin at the germ layer interface. Finally, FGF directs distinct hitherto unrecognised and partially redundant protrusive behaviours during later mesoderm spreading. Cells first move radially towards the ectoderm, and then switch to a dorsally directed movement across its surface. We show that both movements are important for layer formation and present evidence suggesting that they are controlled by genetically distinct mechanisms.
41 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2019 | 2 |
| 2018 | 1 |
| 2015 | 1 |
| 2014 | 1 |
| 2011 | 2 |