scholarly journals ProNodal acts via FGFR3 to govern duration of Shh expression in the prechordal mesoderm

Development ◽  
2015 ◽  
Vol 142 (22) ◽  
pp. 3821-3832 ◽  
Author(s):  
Pamela S. Ellis ◽  
Sarah Burbridge ◽  
Sandrine Soubes ◽  
Kyoji Ohyama ◽  
Nadav Ben-Haim ◽  
...  
Keyword(s):  
Prechordal Mesoderm

A single morphogenetic field gives rise to two retina primordia under the influence of the prechordal plate

Development ◽  
1997 ◽  
Vol 124 (3) ◽  
pp. 603-615 ◽  
Author(s):  
H. Li ◽  
C. Tierney ◽  
L. Wen ◽  
J.Y. Wu ◽  
Y. Rao
Keyword(s):  
Expression Pattern ◽  
Lineage Tracing ◽  
Chick Embryos ◽  
Median Region ◽  
Prechordal Plate ◽  
Prechordal Mesoderm ◽  
New Gene ◽  
Vertebrate Embryos ◽  
Migration Of Cells ◽  
Anterior Neural Plate

Two bilaterally symmetric eyes arise from the anterior neural plate in vertebrate embryos. An interesting question is whether both eyes share a common developmental origin or they originate separately. We report here that the expression pattern of a new gene ET reveals that there is a single retina field which resolves into two separate primordia, a suggestion supported by the expression pattern of the Xenopus Pax-6 gene. Lineage tracing experiments demonstrate that retina field resolution is not due to migration of cells in the median region to the lateral parts of the field. Removal of the prechordal mesoderm led to formation of a single retina both in chick embryos and in Xenopus explants. Transplantation experiments in chick embryos indicate that the prechordal plate is able to suppress Pax-6 expression. Our results provide direct evidence for the existence of a single retina field, indicate that the retina field is resolved by suppression of retina formation in the median region of the field, and demonstrate that the prechordal plate plays a primary signaling role in retina field resolution.

The developmental fate of the cephalic mesoderm in quail-chick chimeras

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 1-15 ◽  
Author(s):  
G.F. Couly ◽  
P.M. Coltey ◽  
N.M. Le Douarin
Keyword(s):  
Neural Crest ◽  
Neural Crest Cells ◽  
Paraxial Mesoderm ◽  
Avian Embryo ◽  
Facial Skeleton ◽  
Developmental Fate ◽  
Prechordal Mesoderm ◽  
The Face ◽  
Neural Crest Origin ◽  
Neurula Stage

The developmental fate of the cephalic paraxial and prechordal mesoderm at the late neurula stage (3-somite) in the avian embryo has been investigated by using the isotopic, isochronic substitution technique between quail and chick embryos. The territories involved in the operation were especially tiny and the size of the transplants was of about 150 by 50 to 60 microns. At that stage, the neural crest cells have not yet started migrating and the fate of mesodermal cells exclusively was under scrutiny. The prechordal mesoderm was found to give rise to the following ocular muscles: musculus rectus ventralis and medialis and musculus oblicus ventralis. The paraxial mesoderm was separated in two longitudinal bands: one median, lying upon the cephalic vesicles (median paraxial mesoderm—MPM); one lateral, lying upon the foregut (lateral paraxial mesoderm—LPM). The former yields the three other ocular muscles, contributes to mesencephalic meninges and has essentially skeletogenic potencies. It contributes to the corpus sphenoid bone, the orbitosphenoid bone and the otic capsules; the rest of the facial skeleton is of neural crest origin. At 3-somite stage, MPM is represented by a few cells only. The LPM is more abundant at that stage and has essentially myogenic potencies with also some contribution to connective tissue. However, most of the connective cells associated with the facial and hypobranchial muscles are of neural crest origin. The more important result of this work was to show that the cephalic mesoderm does not form dermis. This function is taken over by neural crest cells, which form both the skeleton and dermis of the face. If one draws a parallel between the so-called “somitomeres” of the head and the trunk somites, it appears that skeletogenic potencies are reduced in the former, which in contrast have kept their myogenic capacities, whilst the formation of skeleton and dermis has been essentially taken over by the neural crest in the course of evolution of the vertebrate head.

Expression of the LIM class homeobox gene Xlim-1 in pronephros and CNS cell lineages of Xenopus embryos is affected by retinoic acid and exogastrulation

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1525-1536 ◽  
Author(s):  
M. Taira ◽  
H. Otani ◽  
M. Jamrich ◽  
I.B. Dawid
Keyword(s):  
Retinoic Acid ◽  
Organizer Region ◽  
Homeobox Gene ◽  
Second Phase ◽  
Cell Specification ◽  
Spemann Organizer ◽  
Xenopus Embryos ◽  
Prechordal Mesoderm ◽  
The Central Nervous System ◽  
Lateral Mesoderm

The LIM class homeobox gene Xlim-1 is expressed in Xenopus embryos in the lineages leading to (i) the notochord, (ii) the pronephros, and (iii) certain cells of the central nervous system (CNS). In its first expression phase, Xlim-1 mRNA arises in the Spemann organizer region, accumulates in prechordal mesoderm and notochord during gastrulation, and decays in these tissues during neurula stages except that it persists in the posterior tip of the notochord. In the second phase, expression in lateral mesoderm begins at late gastrula, and converges to the pronephros at tailbud stages. Expression in a central location of the neural plate also initiates at late gastrula, expands anteriorly and posteriorly, and becomes established in the lateral regions of the spinal cord and hindbrain at tailbud stages. Thus Xlim-1 expression precedes morphogenesis, suggesting that it may be involved in cell specification in these lineages. Enhancement of Xlim-1 expression by retinoic acid (RA) was first detectable in the dorsal mesoderm at initial gastrula. During gastrulation and early neurulation, RA strongly enhanced Xlim-1 expression in all three lineages and also expanded its expressing domains; this overexpression correlated well with RA phenotypes such as enlarged pronephros and hindbrain-like structure. Exogastrulation reduced Xlim-1 expression in the lateral mesoderm and ectoderm but not in the notochord, suggesting that the second phase of Xlim-1 expression requires mesoderm/ectoderm interactions. RA treatment of exogastrulae did not revert this reduction.

scholarly journals Differential patterning of ventral midline cells by axial mesoderm is regulated by BMP7 and chordin

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 397-408 ◽  
Author(s):  
K. Dale ◽  
N. Sattar ◽  
J. Heemskerk ◽  
J.D. Clarke ◽  
M. Placzek ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Floor Plate ◽  
Neural Plate ◽  
Ventral Midline ◽  
Molecular Events ◽  
Morphogenetic Protein ◽  
Explant Cultures ◽  
Prechordal Mesoderm ◽  
Midline Cells ◽  
Bmp Antagonist

Ventral midline cells in the neural tube have distinct properties at different rostrocaudal levels, apparently in response to differential signalling by axial mesoderm. Floor plate cells are induced by sonic hedgehog (SHH) secreted from the notochord whereas ventral midline cells of the rostral diencephalon (RDVM cells) appear to be induced by the dual actions of SHH and bone morphogenetic protein 7 (BMP7) from prechordal mesoderm. We have examined the cellular and molecular events that govern the program of differentiation of RDVM cells under the influence of the axial mesoderm. By fate mapping, we show that prospective RDVM cells migrate rostrally within the neural plate, passing over rostral notochord before establishing register with prechordal mesoderm at stage 7. Despite the co-expression of SHH and BMP7 by rostral notochord, prospective RDVM cells appear to be specified initially as caudal ventral midline neurectodermal cells and to acquire RDVM properties only at stage 7. We provide evidence that the signalling properties of axial mesoderm over this period are regulated by the BMP antagonist, chordin. Chordin is expressed throughout the axial mesoderm as it extends, but is downregulated in prechordal mesoderm coincident with the onset of RDVM cell differentiation. Addition of chordin to conjugate explant cultures of prechordal mesoderm and neural tissue prevents the rostralization of ventral midline cells by prechordal mesoderm. Chordin may thus act to refine the patterning of the ventral midline along the rostrocaudal axis.

The organizer of the mouse gastrula is composed of a dynamic population of progenitor cells for the axial mesoderm

Development ◽  
2001 ◽  
Vol 128 (18) ◽  
pp. 3623-3634 ◽  
Author(s):  
Simon J. Kinder ◽  
Tania E. Tsang ◽  
Maki Wakamiya ◽  
Hiroshi Sasaki ◽  
Richard R. Behringer ◽  
...  
Keyword(s):  
Primitive Streak ◽  
Cell Populations ◽  
Genetic Activity ◽  
Neural Axis ◽  
Prechordal Mesoderm ◽  
Stage Embryo ◽  
Dynamic Population ◽  
Host Embryo ◽  
Early Gastrula ◽  
Different Parts

An organizer population has been identified in the anterior end of the primitive streak of the mid-streak stage embryo, by the expression of Hnf3β, GsclacZ and Chrd, and the ability of these cells to induce a second neural axis in the host embryo. This cell population can therefore be regarded as the mid-gastrula organizer and, together with the early-gastrula organizer and the node, constitute the organizer of the mouse embryo at successive stages of development. The profile of genetic activity and the tissue contribution by cells in the organizer change during gastrulation, suggesting that the organizer may be populated by a succession of cell populations with different fates. Fine mapping of the epiblast in the posterior region of the early-streak stage embryo reveals that although the early-gastrula organizer contains cells that give rise to the axial mesoderm, the bulk of the progenitors of the head process and the notochord are localized outside the early gastrula organizer. In the mid-gastrula organizer, early gastrula organizer derived cells that are fated for the prechordal mesoderm are joined by the progenitors of the head process that are recruited from the epiblast previously anterior to the early gastrula organizer. Cells that are fated for the head process move anteriorly from the mid-gastrula organizer in a tight column along the midline of the embryo. Other mid-gastrula organizer cells join the expanding mesodermal layer and colonize the cranial and heart mesoderm. Progenitors of the trunk notochord that are localized in the anterior primitive streak of the mid-streak stage embryo are later incorporated into the node. The gastrula organizer is therefore composed of a constantly changing population of cells that are allocated to different parts of the axial mesoderm.

Specification of pharyngeal endoderm is dependent on early signals from axial mesoderm

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4573-4583
Author(s):  
Linda A. Barlow
Keyword(s):  
Embryonic Development ◽  
Taste Buds ◽  
Taste Bud ◽  
General View ◽  
Bud Development ◽  
Pharyngeal Endoderm ◽  
Prechordal Mesoderm

The development of taste buds is an autonomous property of the pharyngeal endoderm, and this inherent capacity is acquired by the time gastrulation is complete. These results are surprising, given the general view that taste bud development is nerve dependent, and occurs at the end of embryogenesis. The pharyngeal endoderm sits at the dorsal lip of the blastopore at the onset of gastrulation, and because this taste bud-bearing endoderm is specified to make taste buds by the end of gastrulation, signals that this tissue encounters during gastrulation might be responsible for its specification. To test this idea, tissue contacts during gastrulation were manipulated systematically in axolotl embryos, and the subsequent ability of the pharyngeal endoderm to generate taste buds was assessed. Disruption of both putative planar and vertical signals from neurectoderm failed to prevent the differentiation of taste buds in endoderm. However, manipulations of contact between presumptive pharyngeal endoderm and axial mesoderm during gastrulation indicate that signals from axial mesoderm (the notochord and prechordal mesoderm) specify the pharyngeal endoderm, conferring upon the endoderm the ability to autonomously differentiate taste buds. These findings further emphasize that despite the late differentiation of taste buds, the tissue-intrinsic mechanisms that generate these chemoreceptive organs are set in motion very early in embryonic development.

Sonic hedgehog signaling at gastrula stages specifies ventral telencephalic cells in the chick embryo

Development ◽  
2000 ◽  
Vol 127 (15) ◽  
pp. 3283-3293 ◽  
Author(s):  
L. Gunhaga ◽  
T.M. Jessell ◽  
T. Edlund
Keyword(s):  
Sonic Hedgehog ◽  
Neural Tube ◽  
Hedgehog Signaling ◽  
Early Stage ◽  
Primitive Streak ◽  
Cell Types ◽  
Neural Cells ◽  
Sonic Hedgehog Signaling ◽  
Ventral Telencephalon ◽  
Prechordal Mesoderm

A secreted signaling factor, Sonic hedgehog (Shh), has a crucial role in the generation of ventral cell types along the entire rostrocaudal axis of the neural tube. At caudal levels of the neuraxis, Shh is secreted by the notochord and floor plate during the period that ventral cell fates are specified. At anterior prosencephalic levels that give rise to the telencephalon, however, neither the prechordal mesoderm nor the ventral neural tube expresses Shh at the time that the overt ventral character of the telencephalon becomes evident. Thus, the precise role and timing of Shh signaling relevant to the specification of ventral telencephalic identity remains unclear. By analysing neural cell differentiation in chick neural plate explants we provide evidence that neural cells acquire molecular properties characteristic of the ventral telencephalon in response to Shh signals derived from the anterior primitive streak/Hensen's node region at gastrula stages. Exposure of prospective anterior prosencephalic cells to Shh at this early stage is sufficient to initiate a temporal program of differentiation that parallels that of neurons generated normally in the medial ganglionic eminence subdivision of the ventral telencephalon.

Induction of floor plate differentiation by contact-dependent, homeogenetic signals

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 205-218 ◽  
Author(s):  
M. Placzek ◽  
T.M. Jessell ◽  
J. Dodd
Keyword(s):  
Axon Guidance ◽  
Neural Tube ◽  
Floor Plate ◽  
Cell Patterning ◽  
Neural Plate ◽  
Neural Cells ◽  
Cellular Mechanisms ◽  
Prechordal Mesoderm ◽  
Specific Antigens ◽  
Inductive Signals

The floor plate is located at the ventral midline of the neural tube and has been implicated in neural cell patterning and axon guidance. To address the cellular mechanisms involved in floor plate differentiation, we have used an assay that monitors the expression of floor-plate-specific antigens in neural plate explants cultured in the presence of inducing tissues. Contact-mediated signals from both the notochord and the floor plate act directly on neural plate cells to induce floor plate differentiation. Floor plate induction is initiated medially by a signal from the notochord, but appears to be propagated to more lateral cells by homeogenetic signals that derive from medial floor plate cells. The response of neural plate cells to inductive signals declines with embryonic age, suggesting that the mediolateral extent of the floor plate is limited by a loss of competence of neural cells. The rostral boundary of the floor plate at the midbrain-forebrain junction appears to result from the lack of inducing activity in prechordal mesoderm and the inability of rostral neural plate cells to respond to inductive signals.

The dorsal involuting marginal zone stiffens anisotropically during its convergent extension in the gastrula of Xenopus laevis

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3131-3140 ◽  
Author(s):  
S.W. Moore ◽  
R.E. Keller ◽  
M.A. Koehl
Keyword(s):  
Extracellular Matrix ◽  
Xenopus Laevis ◽  
Marginal Zone ◽  
Force Production ◽  
Special Property ◽  
Testing Procedure ◽  
Materials Testing ◽  
Convergent Extension ◽  
Cell Matrix ◽  
Prechordal Mesoderm

Physically, the course of morphogenesis is determined by the distribution and timing of force production in the embryo and by the mechanical properties of the tissues on which these forces act. We have miniaturized a standard materials-testing procedure (the stress-relaxation test) to measure the viscoelastic properties of the dorsal involuting marginal zone, prechordal mesoderm, and vegetal endoderm of Xenopus laevis embryos during gastrulation. We focused on the involuting marginal zone, because it undergoes convergent extension (an important and wide-spread morphogenetic process) and drives involution, blastopore closure and elongation of the embryonic axis. We show that the involuting marginal zone stiffens during gastrulation, stiffening is a special property of this region rather than a general property of the whole embryo, stiffening is greater along the anteroposterior axis than the mediolateral axis and changes in the cytoskeleton or extracellular matrix are necessary for stiffening, although changes in cell-cell adhesions or cell-matrix adhesions are not ruled out. These findings provide a baseline of data on which future experiments can be designed and make specific, testable predictions about the roles of the cytoskeleton, extracellular matrix and intercellular adhesion in convergent extension, as well as predictions about the morphogenetic role of convergent extension in early development.

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