The prechordal region lacks neural inducing ability, but can confer anterior character to more posterior neuroepithelium

Development ◽  
1997 ◽  
Vol 124 (15) ◽  
pp. 2983-2996 ◽  
Author(s):  
A.C. Foley ◽  
K.G. Storey ◽  
C.D. Stern
Keyword(s):  
Nervous System ◽  
Molecular Markers ◽  
Primitive Streak ◽  
Neural Fate ◽  
Spemann's Organizer ◽  
Stage 4

The avian equivalent of Spemann's organizer, Hensen's node, begins to lose its ability to induce a nervous system from area opaca epiblast cells at stage 4+, immediately after the full primitive streak stage. From this stage, the node is no longer able to induce regions of the nervous system anterior to the hindbrain. Stage 4+ is marked by the emergence from the node of a group of cells, the prechordal mesendoderm. Here we have investigated whether the prechordal region possesses the lost functions of the organizer, using quail-chick chimaeras to distinguish graft- and host-derived cells, together with several region-specific molecular markers. We find that the prechordal region does not have neural inducing ability, as it is unable to divert extraembryonic epiblast cells to a neural fate. However, it can confer more anterior character to prospective hindbrain cells of the host, making them acquire expression of the forebrain markers tailless and Otx-2. It can also rescue the expression of Krox-20 and Otx-2 from nervous system induced by an older (stage 5) node in extraembryonic epiblast. We show that these properties reflect a true change of fate of cells rather than recruitment from other regions. The competence of neuroectoderm to respond to anteriorizing signals declines by stages 7–9, but both posteriorizing signals and the ability of neuroectoderm to respond to them persist after this stage.

Neural induction and regionalisation in the chick embryo

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 729-741 ◽  
Author(s):  
K.G. Storey ◽  
J.M. Crossley ◽  
E.M. De Robertis ◽  
W.E. Norris ◽  
C.D. Stern
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Molecular Markers ◽  
Chick Embryo ◽  
Normal Development ◽  
Neural Induction ◽  
Stage 4 ◽  
Embryo Chick ◽  
Host Embryo ◽  
Embryonic Region

Induction and regionalisation of the chick nervous system were investigated by transplanting Hensen's node into the extra-embryonic region (area opaca margin) of a host embryo. Chick/quail chimaeras were used to determine the contributions of host and donor tissue to the supernumerary axis, and three molecular markers, Engrailed, neurofilaments (antibody 3A10) and XlHbox1/Hox3.3 were used to aid the identification of particular regions of the ectopic axis. We find that the age of the node determines the regions of the nervous system that form: young nodes (stages 2–4) induced both anterior and posterior nervous system, while older nodes (stages 5–6) have reduced inducing ability and generate only posterior nervous system. By varying the age of the host embryo, we show that the competence of the epiblast to respond to neural induction declines after stage 4. We conclude that during normal development, the initial steps of neural induction take place before stage 4 and that anteroposterior regionalisation of the nervous system may be a later process, perhaps associated with the differentiating notochord. We also speculate that the mechanisms responsible for induction of head CNS differ from those that generate the spinal cord: the trunk CNS could arise by homeogenetic induction by anterior CNS or by elongation of neural primordia that are induced very early.

Reconciling different models of forebrain induction and patterning: a dual role for the hypoblast

Development ◽  
2000 ◽  
Vol 127 (17) ◽  
pp. 3839-3854 ◽  
Author(s):  
A.C. Foley ◽  
I. Skromne ◽  
C.D. Stern
Keyword(s):  
Nervous System ◽  
Molecular Markers ◽  
Regional Identity ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Dual Role ◽  
Visceral Endoderm ◽  
Forebrain Development ◽  
Early Markers

Several models have been proposed for the generation of the rostral nervous system. Among them, Nieuwkoop's activation/transformation hypothesis and Spemann's idea of separate head and trunk/tail organizers have been particularly favoured recently. In the mouse, the finding that the visceral endoderm (VE) is required for forebrain development has been interpreted as support for the latter model. Here we argue that the chick hypoblast is equivalent to the mouse VE, based on fate, expression of molecular markers and characteristic anterior movements around the time of gastrulation. We show that the hypoblast does not fit the criteria for a head organizer because it does not induce neural tissue from naive epiblast, nor can it change the regional identity of neural tissue. However, the hypoblast does induce transient expression of the early markers Sox3 and Otx2. The spreading of the hypoblast also directs cell movements in the adjacent epiblast, such that the prospective forebrain is kept at a distance from the organizer at the tip of the primitive streak. We propose that this movement is important to protect the forebrain from the caudalizing influence of the organizer. This dual role of the hypoblast is more consistent with the Nieuwkoop model than with the notion of separate organizers, and accommodates the available data from mouse and other vertebrates.

Proneural clusters: equivalence groups in the epithelium of Drosophila

Development ◽  
1990 ◽  
Vol 110 (3) ◽  
pp. 927-932 ◽  
Author(s):  
P. Simpson ◽  
C. Carteret
Keyword(s):  
Nervous System ◽  
Cell Lineage ◽  
Cellular Interactions ◽  
Equivalence Group ◽  
Neural Fate ◽  
Axonal Projections ◽  
The Central Nervous System ◽  
Neuronal Specificity ◽  
Proneural Cluster ◽  
Do So

The segregation of neural precursors from epidermal cells during development of the nervous system of Drosophila relies on interactions between cells that are thought to be initially equivalent. During development of the adult peripheral nervous system, failure of the cellular interactions leads to the differentiation of a tuft of sensory bristles at the site where usually only one develops. It is thus thought that a group of cells at that site (a proneural cluster) has the potential to make a bristle but that in normal development only one cell will do so. The question addressed here is do these cells constitute an equivalence group (Kimble, J., Sulston, J. and White, J. (1979). In Cell Lineage, Stem Cells and Cell Determination (ed. N. Le Douarin). Inserm Symposium No. 10 pp. 59–68, Elsevier, Amsterdam)? Within clusters mutant for shaggy, where several cells of a cluster follow the neural fate and differentiate bristles, it is shown that these display identical neuronal specificity: stimulation of the bristles evoke the same leg cleaning response and backfilling of single neurons reveal similar axonal projections in the central nervous system. This provides direct experimental evidence that the cells of a proneural cluster are developmentally equivalent.

Nuclear beta-catenin and the development of bilateral symmetry in normal and LiCl-exposed chick embryos

Development ◽  
1999 ◽  
Vol 126 (13) ◽  
pp. 2955-2965 ◽  
Author(s):  
T. Roeser ◽  
S. Stein ◽  
M. Kessel
Keyword(s):  
Molecular Markers ◽  
Nuclear Localization ◽  
Symmetric Domain ◽  
Primitive Streak ◽  
Bilateral Symmetry ◽  
Beta Catenin ◽  
Developmental Constraints ◽  
Organizing Center ◽  
Developing Area ◽  
Further Development

Studies in Xenopus laevis and zebrafish suggest a key role for beta-catenin in the specification of the axis of bilateral symmetry. In these organisms, nuclear beta-catenin demarcates the dorsalizing centers. We have asked whether beta-catenin plays a comparable role in the chick embryo and how it is adapted to the particular developmental constraints of chick development. The first nuclear localization of beta-catenin is observed in late intrauterine stages of development in the periphery of the blastoderm, the developing area opaca and marginal zone. Obviously, this early, radially symmetric domain does not predict the future organizing center of the embryo. During further development, cells containing nuclear beta-catenin spread under the epiblast and form the secondary hypoblast. The onset of hypoblast formation thus demarcates the first bilateral symmetry in nuclear beta-catenin distribution. Lithium chloride exposure also causes ectopic nuclear localization of beta-catenin in cells of the epiblast in the area pellucida. Embryos treated before primitive streak formation become completely radialized, as shown by the expression of molecular markers, CMIX and GSC. Lithium treatments performed during early or medium streak stages cause excessive development of the anterior primitive streak, node and notochord, and lead to a degeneration of prospective ventral and posterior structures, as shown by the expression of the molecular markers GSC, CNOT1, BMP2 and Ch-Tbx6L. In summary, we found that in spite of remarkable spatiotemporal differences, beta-catenin acts in the chick in a manner similar to that in fish and amphibia.

Induction of cardiac myogenesis in avian pregastrula epiblast: the role of the hypoblast and activin

Development ◽  
1997 ◽  
Vol 124 (13) ◽  
pp. 2561-2570 ◽  
Author(s):  
T.A. Yatskievych ◽  
A.N. Ladd ◽  
P.B. Antin
Keyword(s):  
Heart Development ◽  
Heart Muscle ◽  
Primitive Streak ◽  
Myocardial Cell ◽  
Posterior Region ◽  
Cell Specification ◽  
Potent Inducer ◽  
Vitro Assay ◽  
Cardiac Myogenesis ◽  
Stage 4

An in vitro assay has been developed to investigate tissue interactions regulating myocardial cell specification in birds. Explants from the posterior region of stage XI-XIV blastulas were found to form heart muscle at high frequency with a timing that corresponded to onset of cardiac myocyte differentiation in vivo. Isolation and recombination experiments demonstrated that a signal from the hypoblast was required to induce cardiac myogenesis in the epiblast, and regional differences in epiblast responsiveness and hypoblast inductiveness restrict appearance of cardiac myocytes to the posterior region. Explantation studies provided evidence that myocardial cell specification is underway by stage 3, indicating that the hypoblast-derived signal occurs shortly before specification is detected. Recombinations were also performed to compare cardiac-inducing capacities of pregastrula hypoblast and stage 5 anterior lateral endoderm. The hypoblast possessed broad capacity to induce heart muscle cells in pregastrula and mid-gastrula epiblast, and modest ability to induce cardiac myogenesis in stage 4 posterior primitive streak. Stage 5 anterior lateral endoderm, in contrast, showed no ability to induce heart development in epiblast cells but was a potent inducer of cardiac myogenesis in cells from stage 4 posterior primitive streak. These findings suggest that the hypoblast-derived signal likely acts upstream of proposed heart-inducing signals provided by anterior lateral endoderm. Experiments were also performed to investigate whether activin, or an activin-like molecule, is involved in regulating cardiac myogenesis. Follistatin blocked cardiac myogenesis in stage XI-XIV posterior region explants and activin induced cardiac myogenesis in a dose-dependent fashion in posterior epiblast. These findings indicate that activin, or an activin-like molecule, is required for and is sufficient to stimulate cardiac myogenesis in posterior region pregastrula epiblast. Three models are presented to explain these results.

Ectodermal patterning in the avian embryo: epidermis versus neural plate

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 63-73 ◽  
Author(s):  
E. Pera ◽  
S. Stein ◽  
M. Kessel
Keyword(s):  
Chick Embryo ◽  
Neural Crest ◽  
Plate Boundary ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Neural Plate ◽  
Avian Embryo ◽  
Neural Fate ◽  
Early Stages ◽  
Two Factors

Ectodermal patterning of the chick embryo begins in the uterus and continues during gastrulation, when cells with a neural fate become restricted to the neural plate around the primitive streak, and cells fated to become the epidermis to the periphery. The prospective epidermis at early stages is characterized by the expression of the homeobox gene DLX5, which remains an epidermal marker during gastrulation and neurulation. Later, some DLX5-expressing cells become internalized into the ventral forebrain and the neural crest at the hindbrain level. We studied the mechanism of ectodermal patterning by transplantation of Hensen's nodes and prechordal plates. The DLX5 marker indicates that not only a neural plate, but also a surrounding epidermis is induced in such operations. Similar effects can be obtained with neural plate grafts. These experiments demonstrate that the induction of a DLX5-positive epidermis is triggered by the midline, and the effect is transferred via the neural plate to the periphery. By repeated extirpations of the endoderm we suppressed the formation of an endoderm/mesoderm layer under the epiblast. This led to the generation of epidermis, and to the inhibition of neuroepithelium in the naked ectoderm. This suggests a signal necessary for neural, but inhibitory for epidermal development, normally coming from the lower layers. Finally, we demonstrate that BMP4, as well as BMP2, is capable of inducing epidermal fate by distorting the epidermis-neural plate boundary. This, however, does not happen independently within the neural plate or outside the normal DLX5 domain. In the area opaca, the co-transplantation of a BMP4 bead with a node graft leads to the induction of DLX5, thus indicating the cooperation of two factors. We conclude that ectodermal patterning is achieved by signalling both from the midline and from the periphery, within the upper but also from the lower layers.

scholarly journals Putative oncogene Brachyury (T) is essential to specify cell fate but dispensable for notochord progenitor proliferation and EMT

2016 ◽  
Vol 113 (14) ◽  
pp. 3820-3825 ◽  
Author(s):  
Jianjian Zhu ◽  
Kin Ming Kwan ◽  
Susan Mackem
Keyword(s):  
Cell Fate ◽  
Epithelial Mesenchymal Transition ◽  
Primitive Streak ◽  
Lineage Tracing ◽  
Genetic Lineage ◽  
Mesenchymal Transition ◽  
Neural Fate ◽  
Notochord Cell ◽  
Genetic Lineage Tracing ◽  
And Function

The transcription factor Brachyury (T) gene is expressed throughout primary mesoderm (primitive streak and notochord) during early embryonic development and has been strongly implicated in the genesis of chordoma, a sarcoma of notochord cell origin. Additionally, T expression has been found in and proposed to play a role in promoting epithelial–mesenchymal transition (EMT) in various other types of human tumors. However, the role of T in normal mammalian notochord development and function is still not well-understood. We have generated an inducible knockdown model to efficiently and selectively deplete T from notochord in mouse embryos. In combination with genetic lineage tracing, we show that T function is essential for maintaining notochord cell fate and function. Progenitors adopt predominantly a neural fate in the absence of T, consistent with an origin from a common chordoneural progenitor. However, T function is dispensable for progenitor cell survival, proliferation, and EMT, which has implications for the therapeutic targeting of T in chordoma and other cancers.

scholarly journals Self-organization of a functional human organizer by combined WNT and NODAL signalling

2017 ◽  
Author(s):  
I. Martyn ◽  
T.Y. Kanno ◽  
A. Ruzo ◽  
E.D. Siggia ◽  
A.H. Brivanlou
Keyword(s):  
Epithelial To Mesenchymal Transition ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Model Organisms ◽  
Detailed Characterization ◽  
Mesenchymal Transition ◽  
Neural Fate ◽  
Secondary Axis ◽  
Human Embryology ◽  
Emt Markers

In amniotes, the development of the primitive streak (PS) and its accompanying “organizer” define the first stages of gastrulation. Despite detailed characterization in model organisms, the analogous human structures remain a mystery. We have previously shown that when stimulated with BMP4, micropatterned colonies of human embryonic stem cells (hESCs) self-organize to generate early embryonic germ layers1. Here we show that in the same type of colonies WNT signalling is sufficient to induce a PS, and WNT with ACTIVIN is sufficient to induce an organizer, as characterized by embryo-like sharp boundary formation, epithelial-to-mesenchymal transition (EMT) markers, and expression of the organizer specific transcription factor GSC. Moreover, when grafted into chick embryos, WNT and ACTIVIN treated human cells induce and contribute autonomously to a secondary axis while inducing neural fate in the host. This fulfills the most stringent functional criteria for an organizer, and its discovery represents a major milestone in human embryology.

scholarly journals Central nervous system relapse in high-risk stage 4 neuroblastoma: The HR-NBL1/SIOPEN trial experience

2021 ◽  
Vol 144 ◽  
pp. 1-8
Author(s):  
P. Berlanga ◽  
C. Pasqualini ◽  
U. Pötschger ◽  
C. Sangüesa ◽  
M.R. Castellani ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
High Risk ◽  
Central Nervous System Relapse ◽  
Trial Experience ◽  
Stage 4

The L5 epitope: an early marker for neural induction in the chick embryo and its involvement in inductive interactions

Development ◽  
1991 ◽  
Vol 112 (4) ◽  
pp. 959-970 ◽  
Author(s):  
C. Roberts ◽  
N. Platt ◽  
A. Streit ◽  
M. Schachner ◽  
C.D. Stern
Keyword(s):  
Nervous System ◽  
Chick Embryo ◽  
Neural Induction ◽  
Primitive Streak ◽  
Hybridoma Cells ◽  
Minor Components ◽  
Lower Molecular Mass ◽  
Host Embryo ◽  
Donor Embryo ◽  
Developing Nervous System

The pattern of expression of the carbohydrate epitope L5 was studied during early development of the chick neuroepithelium. Immunoreactivity first appears during gastrulation, at mid-primitive streak stage, and persists until at least 3.5 days of development. The epitope is expressed on all the components of the developing nervous system, both central and peripheral. In immunoblots, the antibody recognises a major component of about Mr 500,000 and several more minor components of lower molecular mass. If a Hensen's node from a donor embryo is transplanted into the area opaca of a host embryo, L5 immunoreactivity appears in the epiblast surrounding the graft. If hybridoma cells secreting the antibody are grafted together with Hensen's node into a host chick embryo, the induction of a supernumerary nervous system is inhibited. We suggest that the L5 epitope is an early and general marker for neural induction and that it may be involved directly in inductive interactions.

Sign in / Sign up

Export Citation Format

Share Document