Cell movements during epiboly and gastrulation in zebrafish

Development ◽  
1990 ◽  
Vol 108 (4) ◽  
pp. 569-580 ◽  
Author(s):  
R.M. Warga ◽  
C.B. Kimmel
Keyword(s):  
Dorsal Side ◽  
Epithelial Layer ◽  
Convergent Extension ◽  
Blastula Stage ◽  
Cell Movements ◽  
Yolk Cell ◽  
Radial Cell ◽  
Convergence And Extension ◽  
Embryonic Ectoderm ◽  
Anterior Posterior

Beginning during the late blastula stage in zebrafish, cells located beneath a surface epithelial layer of the blastoderm undergo rearrangements that accompany major changes in shape of the embryo. We describe three distinctive kinds of cell rearrangements. (1) Radial cell intercalations during epiboly mix cells located deeply in the blastoderm among more superficial ones. These rearrangements thoroughly stir the positions of deep cells, as the blastoderm thins and spreads across the yolk cell. (2) Involution at or near the blastoderm margin occurs during gastrulation. This movement folds the blastoderm into two cellular layers, the epiblast and hypoblast, within a ring (the germ ring) around its entire circumference. Involuting cells move anteriorwards in the hypoblast relative to cells that remain in the epiblast; the movement shears the positions of cells that were neighbors before gastrulation. Involuting cells eventually form endoderm and mesoderm, in an anterior-posterior sequence according to the time of involution. The epiblast is equivalent to embryonic ectoderm. (3) Mediolateral cell intercalations in both the epiblast and hypoblast mediate convergence and extension movements towards the dorsal side of the gastrula. By this rearrangement, cells that were initially neighboring one another become dispersed along the anterior-posterior axis of the embryo. Epiboly, involution and convergent extension in zebrafish involve the same kinds of cellular rearrangements as in amphibians, and they occur during comparable stages of embryogenesis.

Cell rearrangement and segmentation in Xenopus: direct observation of cultured explants

Development ◽  
1989 ◽  
Vol 105 (1) ◽  
pp. 155-166 ◽  
Author(s):  
P.A. Wilson ◽  
G. Oster ◽  
R. Keller
Keyword(s):  
Explant Culture ◽  
Dorsal Side ◽  
Convergent Extension ◽  
Cell Behaviour ◽  
Cell Rearrangement ◽  
Radial Cell ◽  
Cell Intercalation ◽  
First Time ◽  
The Relationship ◽  
Somitic Mesoderm

We make use of a novel system of explant culture and high resolution video-film recording to analyse for the first time the cell behaviour underlying convergent extension and segmentation in the somitic mesoderm of Xenopus. We find that a sequence of activities sweeps through the somitic mesoderm from anterior to posterior during gastrulation and neurulation, beginning with radial cell intercalation or thinning, continuing with mediolateral intercalation and cell elongation, and culminating in segmentation and somite rotation. Radial intercalation at the posterior tip lengthens the tissue, while mediolateral intercalation farther anterior converges it toward the midline. This extension of the somitic mesoderm helps to elongate the dorsal side of intact neurulae. By separating tissues, we demonstrate that cell rearrangement is independent of the notochord, but radial intercalation - and thus the bulk of extension - requires the presence of an epithelium, either endodermal or ectodermal. Segmentation, on the other hand, can proceed in somitic mesoderm isolated at the end of gastrulation. Finally, we discuss the relationship between cell rearrangement and segmentation.

scholarly journals Regional expression, pattern and timing of convergence and extension during gastrulation of Xenopus laevis

Development ◽  
1988 ◽  
Vol 103 (1) ◽  
pp. 193-209 ◽  
Author(s):  
R. Keller ◽  
M. Danilchik
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Marginal Zone ◽  
Time Lapse ◽  
Dorsal Side ◽  
Convergent Extension ◽  
Intact Embryo ◽  
Convergence And Extension ◽  
Degree Of Convergence ◽  
Degree Of Extension

We show with time-lapse micrography that narrowing in the circumblastoporal dimension (convergence) and lengthening in the animal-vegetal dimension (extension) of the involuting marginal zone (IMZ) and the noninvoluting marginal zone (NIMZ) are the major tissue movements driving blastopore closure and involution of the IMZ during gastrulation in the South African clawed frog, Xenopus laevis. Analysis of blastopore closure shows that the degree of convergence is uniform from dorsal to ventral sides, whereas the degree of extension is greater on the dorsal side of the gastrula. Explants of the gastrula show simultaneous convergence and extension in the dorsal IMZ and NIMZ. In both regions, convergence and extension are most pronounced at their common boundary, and decrease in both animal and vegetal directions. Convergent extension is autonomous to the IMZ and begins at stage 10.5, after the IMZ has involuted. In contrast, expression of convergent extension in the NIMZ appears to be dependent on basal contact with chordamesoderm or with itself. The degree of extension decreases progressively in lateral and ventral sectors. Isolated ventral sectors show convergence without a corresponding degree of extension, perhaps reflecting the transient convergence and thickening that occurs in this region of the intact embryo. We present a detailed mechanism of how these processes are integrated with others to produce gastrulation. The significance of the regional expression of convergence and extension in Xenopus is discussed and compared to gastrulation in other amphibians.

A functional test for maternally inherited cadherin in Xenopus shows its importance in cell adhesion at the blastula stage

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 49-57 ◽  
Author(s):  
J. Heasman ◽  
D. Ginsberg ◽  
B. Geiger ◽  
K. Goldstone ◽  
T. Pratt ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Protein Level ◽  
Mrna Level ◽  
Functional Test ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Xenopus Development ◽  
Dose Dependent ◽  
Embryonic Ectoderm ◽  
E Cadherin

We report here on the consequences of reducing the expression of EP-cadherin at the earliest stages of Xenopus development. Injection of oligodeoxynucleotides antisense to maternal EP-cadherin mRNA into full-grown oocytes reduced the mRNA level in oocytes, and the protein level in blastulae. Adhesion between blastomeres was significantly reduced, as seen in whole embryos, and in assays of the ability of blastomeres to reaggregate in culture. This effect was especially conspicuous in the inner cells of the blastula and included the disruption of the blastocoel. The severity of the EP-cadherin mRNA depletion and of the disaggregation phenotype was dose dependent. This phenotype was rescued by the injection into EP-cadherin mRNA-depleted oocytes of the mRNA coding for a related cadherin, E-cadherin, that is normally expressed at the gastrula stage in the embryonic ectoderm.

In vitro development of inner cell masses isolated immunosurgically from mouse blastocysts

Development ◽  
1978 ◽  
Vol 45 (1) ◽  
pp. 93-105
Author(s):  
Brigid Hogan ◽  
Rita Tilly
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Giant Cells ◽  
Epithelial Layer ◽  
Visceral Endoderm ◽  
Limited Region ◽  
In Vitro Development ◽  
Vitro Development ◽  
Embryonic Ectoderm

This paper describes the in vitro development of inner cell masses isolated immunosurgically from mouse blastocysts which had been collected on 3·5 days p.c. and then incubated for 24 h. The inner cell masses continue to grow in culture and develop through a series of stages with increasing complexity of internal organization. By day 1 all of the cultured ICMs have an outer layer of endoderm, and by day 3 some of them have two distinct kinds of inside cells; a columnar epithelial layer and a thin hemisphere of elongated cells. Later, mesodermal cells appear to delaminate from a limited region of the columnar layer, close to where it forms a junction with the thinner cells. By day 5, about 25% of the cultured ICMs have a striking resemblance to normal 7·5-day p.c. C3H embryos, with embryonic ectoderm, extra-embryonic ectoderm and chorion, embryonic and extra-embryonic mesoderm, and visceral endoderm. When mechanically disrupted and grown as attached clumps of cells in a tissue dish, these embryo-like structures give rise to trophoblast-like giant cells. These results suggest that the inner cell mass of 4·5-day p.c. blastocysts contains cells which can give rise to trophoblast derivates in culture.

scholarly journals Wnt5b integrates Fak1a to mediate gastrulation cell movements via Rac1 and Cdc42

Open Biology ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 190273
Author(s):  
I-Chen Hung ◽  
Tsung-Ming Chen ◽  
Jing-Ping Lin ◽  
Yu-Ling Tai ◽  
Tang-Long Shen ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Early Embryogenesis ◽  
Actin Dynamics ◽  
Convergent Extension ◽  
Cortical Actin ◽  
Functional Interaction ◽  
Cell Movements ◽  
Cellular Pathways ◽  
Antisense Morpholino ◽  
Subthreshold Level

Focal adhesion kinase (FAK) mediates vital cellular pathways during development. Despite its necessity, how FAK regulates and integrates with other signals during early embryogenesis remains poorly understood. We found that the loss of Fak1a impaired epiboly, convergent extension and hypoblast cell migration in zebrafish embryos. We also observed a clear disturbance in cortical actin at the blastoderm margin and distribution of yolk syncytial nuclei. In addition, we investigated a possible link between Fak1a and a well-known gastrulation regulator, Wnt5b, and revealed that the overexpression of fak1a or wnt5b could cross-rescue convergence defects induced by a wnt5b or fak1a antisense morpholino (MO), respectively. Wnt5b and Fak1a were shown to converge in regulating Rac1 and Cdc42, which could synergistically rescue wnt5b and fak1a morphant phenotypes. Furthermore, we generated several alleles of fak1a mutants using CRISPR/Cas9, but those mutants only revealed mild gastrulation defects. However, injection of a subthreshold level of the wnt5b MO induced severe gastrulation defects in fak1a mutants, which suggested that the upregulated expression of wnt5b might complement the loss of Fak1a. Collectively, we demonstrated that a functional interaction between Wnt and FAK signalling mediates gastrulation cell movements via the possible regulation of Rac1 and Cdc42 and subsequent actin dynamics.

scholarly journals Furry is required for cell movements during gastrulation and functionally interacts with NDR1

2020 ◽  
Author(s):  
Ailen S. Cervino ◽  
Bruno Moretti ◽  
Carsten Stuckenholz ◽  
Hernán E. Grecco ◽  
Lance A. Davidson ◽  
...  
Keyword(s):  
Asymmetric Cell Division ◽  
Cell Polarization ◽  
Convergent Extension ◽  
Cellular Functions ◽  
Embryonic Axes ◽  
Cell Movements ◽  
Evolutionarily Conserved ◽  
Axis Elongation ◽  
Established Cell ◽  
Division Cell

AbstractGastrulation is a key event in animal embryogenesis during which the germ layers precursors are rearranged and the embryonic axes are established. Cell polarization is essential during gastrulation driving asymmetric cell division, cell movements and cell shape changes. Furry (Fry) gene encodes an evolutionarily conserved protein with a wide variety of cellular functions mostly related to cell polarization and morphogenesis in invertebrates. However, little is known about its function in vertebrate development. Here we show that in Xenopus, Fry participates in the regulation of morphogenetic processes during gastrulation. Using morpholino knock-down, we demonstrate a role of Fry in blastopore closure and dorsal axis elongation. Loss of Fry function drastically affects the movement and morphological polarization of cells during gastrulation, in addition to dorsal mesoderm convergent extension, responsible for head-to-tail elongation. Finally, we demonstrate a functional interaction between Fry and NDR1 kinase, providing evidence of an evolutionarily conserved complex required for morphogenesis.

scholarly journals Anterior expansion and posterior addition to the notochord mechanically coordinate embryo axis elongation

2021 ◽  
Author(s):  
Susannah B.P. McLaren ◽  
Benjamin J. Steventon
Keyword(s):  
Cell Expansion ◽  
Zebrafish Embryo ◽  
Volumetric Growth ◽  
Cell Ablation ◽  
Notochord Cell ◽  
Convergence And Extension ◽  
Axis Elongation ◽  
Notochord Cells ◽  
The Impact ◽  
Anterior Posterior

AbstractDuring development the embryo body progressively elongates from head-to-tail along the anterior-posterior (AP) axis. Multiple tissues contribute to this elongation through a combination of convergence and extension and/or volumetric growth. How force generated by the morphogenesis of one tissue impacts the morphogenesis of other axial tissues to achieve an elongated axis is not well understood. The notochord, a rod-shaped tissue possessed by all vertebrates, runs across the entire length of the somitic compartment and is flanked on either side by the developing somites in the segmented region of the axis and presomitic mesoderm in the posterior. Cells in the notochord undergo an expansion that is constrained by a stiff sheath of extracellular matrix, that increases the internal pressure in the notochord allowing it to straighten and elongate. Therefore, it is appropriately positioned to play a role in mechanically elongating the somitic compartment. Here, we use multi-photon mediated cell ablation to remove specific regions of the developing notochord and quantify the impact on axis elongation. We show that anterior notochord cell expansion generates a force that displaces notochord cells posteriorly relative to adjacent axial tissues and contributes to the elongation of segmented tissue during post-tailbud stages of development. Crucially, unexpanded cells derived from progenitors at the posterior end of the notochord provide resistance to anterior notochord cell expansion, allowing for force generation across the AP axis. Therefore, notochord cell expansion beginning in the anterior, and addition of cells to the posterior notochord, act as temporally coordinated morphogenetic events that shape the zebrafish embryo AP axis.

scholarly journals Self-organised symmetry breaking in zebrafish reveals feedback from morphogenesis to pattern formation

2019 ◽  
Author(s):  
Vikas Trivedi ◽  
Timothy Fulton ◽  
Andrea Attardi ◽  
Kerim Anlas ◽  
Chaitanya Dingare ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Symmetry Breaking ◽  
Embryonic Stem ◽  
Break Symmetry ◽  
Early Embryo ◽  
Beta Catenin ◽  
Embryonic Cells ◽  
Convergence And Extension ◽  
Extensive Cell ◽  
Anterior Posterior

A fundamental question in developmental biology is how the early embryo breaks initial symmetry to establish the spatial coordinate system later important for the organisation of the embryonic body plan. In zebrafish, this is thought to depend on the inheritance of maternal mRNAs [1–3], cortical rotation to generate a dorsal pole of beta-catenin activity [4–8] and the release of Nodal signals from the yolk syncytial layer (YSL) [9–12]. Recent work aggregating mouse embryonic stem cells has shown that symmetry breaking can occur in the absence of extra-embryonic tissue [19,20]. To test whether this is also true in zebrafish, we separated embryonic cells from the yolk and allowed them to develop as aggregates. These aggregates break symmetry autonomously to form elongated structures with an anterior-posterior pattern. Extensive cell mixing shows that any pre-existing asymmetry is lost prior to the breaking morphological symmetry, revealing that the maternal pre-pattern is not strictly required for early embryo patterning. Following early signalling events after isolation of embryonic cells reveals that a pole of Nodal activity precedes and is required for elongation. The blocking of PCP-dependent convergence and extension movements disrupts the establishment of opposing poles of BMP and Wnt/TCF activity and the patterning of anterior-posterior neural tissue. These results lead us to suggest that convergence and extension plays a causal role in the establishment of morphogen gradients and pattern formation during zebrafish gastrulation.

scholarly journals The patterning and functioning of protrusive activity during convergence and extension of the Xenopus organiser

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 81-91 ◽  
Author(s):  
Ray Keller ◽  
John Shih ◽  
Carmen Domingo
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Marginal Zone ◽  
Tissue Differentiation ◽  
Tissue Interactions ◽  
Dorsal Mesoderm ◽  
Convergence And Extension ◽  
Early Gastrula ◽  
Ventral Explants ◽  
Anterior Posterior

We discuss the cellular basis and tissue interactions regulating convergence and extension of the vertebrate body axis in early embryogenesls of Xenopus. Convergence and extension occur in the dorsal mesoderm (prospective notochord and somite) and in the posterior nervous system (prospective hindbrain and spinal cord) by sequential cell intercalations. Several layers of cells intercalate to form a thinner, longer array (radial intercalation) and then cells intercalate in the mediolateral orientation to form a longer, narrower array (mediolateral intercalation). Fluorescence microscopy of labeled mesodermal cells in explants shows that protrusive activity is rapid and randomly directed until the midgastrula stage, when it slows and is restricted to the medial and lateral ends of the cells. This bipolar protrusive activity results in elongation, alignment and mediolateral intercalation of the cells. Mediolateral intercalation behavior (MIB) is expressed in an anterior-posterior and lateral-medial progression in the mesoderm. MIB is first expressed laterally in both somitic and notochordal mesoderm. From its lateral origins in each tissue, MIB progresses medially. If convergence does not bring the lateral boundaries of the tissues closer to the medial cells in the notochordal and somitic territories, these cells do not express MIB. Expression of tissue-specific markers follows and parallels the expression of MIB. These facts argue that MIB and some aspects of tissue differentiation are induced by signals emanating from the lateral boundaries of the tissue territories and that convergence must bring medial cells and boundaries closer together for these signals to be effective. Grafts of dorsal marginal zone epithelium to the ventral sides of other embryos, to ventral explants and to UV-ventralized embryos show that it has a role in organising convergence and extension, and dorsal tissue differentiation among deep mesodermal cells. Grafts of involuting marginal zone to animal cap tissue of the early gastrula shows that convergence and extension of the hindbrain-spinal cord are induced by planar signals from the involuting marginal zone.

Sign in / Sign up

Export Citation Format

Share Document