scholarly journals The Behaviour of Grafts of Primitive Streak Beneath the Primitive Streak of the Chick

1937 ◽  
Vol 14 (3) ◽  
pp. 319-334 ◽  
Author(s):  
M. ABERCROMBIE ◽  
C. H. WADDINGTON
Keyword(s):  
Neural Tissue ◽  
Primitive Streak ◽  
Lateral Plate ◽  
Secondary Axis ◽  
Regional Character ◽  
Host Tissues

1. Grafts consisting of pieces of primitive streak from blastoderms in the primitive streak stage were placed under the primitive streak of blastoderms also in this stage. 2. Various effects of the host on the graft are described, particularly the reversal of the antero-posterior orientation of the graft, the alteration of the regional character of the graft so as to conform with the host tissues at the same level, the suppression of differentiation in the posterior end of the primitive streak, and the incorporation of the graft tissues into the host. 3. A considerable number of inductions occurred, since the host axis often apparently shifts to one side of the graft. The inductions are of two kinds, the normal evocation by graft mesoderm, resulting usually in the formation of superfluous neural tissue; and the complementary induction of a normal secondary axis, which it is supposed is most often due to the preliminary induction of a primitive streak in the host. 4. Various effects of the graft on the host occur. In particular the disturbance of the head mesenchyme suggests that foregut diverticula are produced where head mesenchyme joins lateral plate mesothelium.

Studies on self-differentiating and induction capacities of Hensen's node using intracoelomic grafting technique

Development ◽  
1972 ◽  
Vol 28 (3) ◽  
pp. 547-558
Author(s):  
J. R. Viswanath ◽  
Leela Mulherkar
Keyword(s):  
Chick Embryo ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Germ Layer ◽  
Grafting Technique ◽  
Definite Combination

Living Hensen's node of the definitive primitive streak of chick embryo was prepared into ‘sandwiches’ with the competent ectoderm and the sandwich grafts were transplated into the 2·5 day chick embryo using the intracoelomic grafting technique of Hamburger. One hundred and twenty-four grafts were prepared and transplanted intracoelomically, 28 grafts were lost due to the death of the host embryos, 63 grafts did not differentiate at all, but 33 well-defined grafts were recovered, after cultivating the transplanted hosts for 12–14 days. All kinds of tissues from feather germs to neural tissue were found to have differentiated in the grafts. The more frequently occurring tissues were feather germs, epidermal vesicle, neural tissue, kidney and muscle. Other differentiations were the cartilage notochord and gut. No definite combination pattern has emerged from the tissues. But when the tissues were traced to their germ-layer derivation, 22 of them belonged to the mesodermal complex, 11 to the ectodermal complex and 8 to the endodermal complex. In the light of the above results, the probable existence of a mesodermal factor and an ectodermal factor independently responsible for the respective differentiations, as also the competence of the ectoderm, is discussed.

scholarly journals Experiments on the Development of the Head of the Chick Embryo

1936 ◽  
Vol 13 (2) ◽  
pp. 219-236
Author(s):  
C. H. WADDINGTON ◽  
A. COHEN
Keyword(s):  
Thin Sheet ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Neural Plate ◽  
Head Region ◽  
Process Stage ◽  
Optic Vesicles ◽  
Lens Formation ◽  
Embryonic Ectoderm

1. Experiments were made on the development of the head of chicken embryos cultivated in vitro. 2. Defects in the presumptive head region of primitive streak embryos are regulated completely if the wound fills up before the histogenesis of neural tissue begins in the head-process stage. Different methods by which the hole is filled are described. 3. No repair occurs in the head-process and head-fold stages, and in this period two masses of neural tissue cannot heal together. 4. Median defects, even if repaired as regards neural tissue, cause a failure of the ventral closure of the foregut. The lateral evaginations of the gut develop typically in atypical situations. The headfold may break through and join up with the endoderm in such a way that the gut acquires an anterior opening. 5. The paired heart rudiments may develop separately. The separate vesicles begin to contract at a time appropriate to the development of the embryo as a whole. The two hearts are mirror images, the left one having the normal curvature, but the embryos do not survive long enough for the hearts to acquire a very definite shape. 6. The forebrain has a considerable capacity for repair in the early somite stages (five to twenty-five somites). One-half of the forebrain can remodel itself into a complete forebrain. In some cases the neural plate and epidermis grow together over the wound, in others the epidermis and mesenchyme make the first covering, leaving a space along the inside of which the neural tissue grows. The neural tissue may become a very thin sheet. 7. The repaired forebrain may induce the formation of a nasal placode from the non-presumptive nasal epidermis which covers the wound. 8. If the optic vesicle is entirely removed, a new one is not formed, but parts of the vesicle can regulate to complete eye-cups, either when still attached to the forebrain or after being isolated in the extra-embryonic regions of another embryo. 9. Injured optic vesicles induce lenses from the non-presumptive epidermis which grows over the wound. Transplanted optic neural tissue from embryos of about five somites induces the formation of lentoids from extra-embryonic ectoderm, but only in a small proportion of cases. 10. The presumptive lens epidermis can produce a slight thickening even when contact with the optic cup is prevented. 11. The significance of periods of minimum regulatory power for the concept of determination is discussed. 12. The data concerning lens formation are discussed in terms of the field concept.

Early posterior neural tissue is induced by FGF in the chick embryo

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 473-484 ◽  
Author(s):  
K.G. Storey ◽  
A. Goriely ◽  
C.M. Sargent ◽  
J.M. Brown ◽  
H.D. Burns ◽  
...  
Keyword(s):  
Chick Embryo ◽  
Cell Fate ◽  
Neural Induction ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Specific Aspect ◽  
Amphibian Embryo ◽  
Fgf Signalling ◽  
Unique Cell ◽  
Neural Cell Fate

Signals that induce neural cell fate in amniote embryos emanate from a unique cell population found at the anterior end of the primitive streak. Cells in this region express a number of fibroblast growth factors (FGFs), a group of secreted proteins implicated in the induction and patterning of neural tissue in the amphibian embryo. Here we exploit the large size and accessibility of the early chick embryo to analyse the function of FGF signalling specifically during neural induction. Our results demonstrate that extraembryonic epiblast cells previously shown to be responsive to endogenous neural-inducing signals express early posterior neural genes in response to local, physiological levels of FGF signal. This neural tissue does not express anterior neural markers or undergo neuronal differentiation and forms in the absence of axial mesoderm. Prospective mesodermal tissue is, however, induced and we present evidence for both the direct and indirect action of FGFs on prospective posterior neural tissue. These findings suggest that FGF signalling underlies a specific aspect of neural induction, the initiation of the programme that leads to the generation of the posterior central nervous system.

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 Experiments on Embryonic Induction

1934 ◽  
Vol 11 (3) ◽  
pp. 218-223
Author(s):  
C. H. WADDINGTON
Keyword(s):  
Recent Work ◽  
Primitive Streak ◽  
Chemical Substance ◽  
Boiling Water ◽  
Direct Result ◽  
Embryonic Induction ◽  
Embryonic Axes ◽  
Chick Blastoderm ◽  
Dead Material ◽  
Regional Character

1. Two cases of induction by coagulated organisers in the chick are described. The implants consisted of pieces of chick primitive streak, and previous to implantation they were killed and coagulated by immersion in boiling water. After this treatment they still retained the inducing capacity which they have been previously shown to possess in the live state. 2. Grafts of dead material into the chick blastoderm usually become enveloped in mesenchyme and thus isolated from the host ectoderm. 3. It is argued that, although there may in the normal egg be a gradient of inducing capacity, the inducing factor itself cannot be a gradient as such: and reference is made to the most recent work which shows that the factor is actually a chemical substance. 4. It is pointed out that there is as yet no evidence that dead organisers can determine the regional character of the embryonic axes which they induce, as live organisers can. 5. In one of the specimens described, the induced axis is accompanied by induced notochord. The question is raised as to whether this notochord is the direct result of the inducing stimulus acting on the host ectoderm, or whether the influence of the host's individuation field has played a part in its formation.

Chordin regulates primitive streak development and the stability of induced neural cells, but is not sufficient for neural induction in the chick embryo

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 507-519 ◽  
Author(s):  
A. Streit ◽  
K.J. Lee ◽  
I. Woo ◽  
C. Roberts ◽  
T.M. Jessell ◽  
...  
Keyword(s):  
Neural Induction ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Neural Plate ◽  
Neural Cells ◽  
Morphogenetic Protein ◽  
Neural Markers ◽  
Bmp Signalling ◽  
The Stability ◽  
Area Pellucida

We have investigated the role of Bone Morphogenetic Protein 4 (BMP-4) and a BMP antagonist, chordin, in primitive streak formation and neural induction in amniote embryos. We show that both BMP-4 and chordin are expressed before primitive streak formation, and that BMP-4 expression is downregulated as the streak starts to form. When BMP-4 is misexpressed in the posterior area pellucida, primitive streak formation is inhibited. Misexpression of BMP-4 also arrests further development of Hensen's node and axial structures. In contrast, misexpression of chordin in the anterior area pellucida generates an ectopic primitive streak that expresses mesoderm and organizer markers. We also provide evidence that chordin is not sufficient to induce neural tissue in the chick. Misexpression of chordin in regions outside the future neural plate does not induce the early neural markers L5, Sox-3 or Sox-2. Furthermore, neither BMP-4 nor BMP-7 interfere with neural induction when misexpressed in the presumptive neural plate before or after primitive streak formation. However, chordin can stabilise the expression of early neural markers in cells that have already received neural inducing signals. These results suggest that the regulation of BMP signalling by chordin plays a role in primitive streak formation and that chordin is not sufficient to induce neural tissue.

The forkhead transcription factor Foxf1 is required for differentiation of extra-embryonic and lateral plate mesoderm

Development ◽  
2001 ◽  
Vol 128 (2) ◽  
pp. 155-166 ◽  
Author(s):  
M. Mahlapuu ◽  
M. Ormestad ◽  
S. Enerback ◽  
P. Carlsson
Keyword(s):  
Transcription Factor ◽  
Cell Adhesion ◽  
Posterior Part ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Yolk Sac ◽  
Lateral Plate Mesoderm ◽  
Forkhead Transcription Factor ◽  
Lateral Plate ◽  
Adhesion Properties

The murine Foxf1 gene encodes a forkhead transcription factor expressed in extra-embryonic and lateral plate mesoderm and later in splanchnic mesenchyme surrounding the gut and its derivatives. We have disrupted Foxf1 and show that mutant embryos die at midgestation due to defects in mesodermal differentiation and cell adhesion. The embryos do not turn and become deformed by the constraints of a small, inflexible amnion. Extra-embryonic structures exhibit a number of differentiation defects: no vasculogenesis occurs in yolk sac or allantois; chorioallantoic fusion fails; the amnion does not expand with the growth of the embryo, but misexpresses vascular and hematopoietic markers. Separation of the bulk of yolk sac mesoderm from the endodermal layer and adherence between mesoderm of yolk sac and amnion, indicate altered cell adhesion properties and enhanced intramesodermal cohesion. A possible cause of this is misexpression of the cell-adhesion protein VCAM1 in Foxf1-deficient extra-embryonic mesoderm, which leads to co-expression of VCAM with its receptor, alpha(4)-integrin. The expression level of Bmp4 is decreased in the posterior part of the embryo proper. Consistent with this, mesodermal proliferation in the primitive streak is reduced and somite formation is retarded. Expression of Foxf1 and the homeobox gene Irx3 defines the splanchnic and somatic mesodermal layers, respectively. In Foxf1-deficient embryos incomplete separation of splanchnic and somatic mesoderm is accompanied by misexpression of Irx3 in the splanchnopleure, which implicates Foxf1 as a repressor of Irx3 and as a factor involved in coelom formation.

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.

An early marker of axial pattern in the chick embryo and its respecification by retinoic acid

Development ◽  
1992 ◽  
Vol 114 (4) ◽  
pp. 841-852 ◽  
Author(s):  
O. Sundin ◽  
G. Eichele
Keyword(s):  
Retinoic Acid ◽  
Chick Embryo ◽  
Protein A ◽  
Ectopic Expression ◽  
Primitive Streak ◽  
Expression Domain ◽  
Lateral Plate ◽  
Antibody Staining ◽  
Discrete Band ◽  
Stage Embryo

Chick Ghox 2.9 protein, a homeodomain-containing polypeptide, is first detected in the mid-gastrula stage embryo and its levels increase rapidly in the late gastrula. At this time, the initially narrow band of expression along the primitive streak expands laterally to form a shield-like domain that encompasses almost the entire posterior region of the embryo and extends anteriorly as far as Hensen's node. We have found that this expression domain co-localizes with a morphological feature that consists of a stratum of refractile, thickened mesoderm. Antibody-staining indicates that Ghox 2.9 protein is present in all cells of this mesodermal region. In contrast, expression within the ectoderm overlying the region of refractile mesoderm varies considerably. The highest levels of expression are found in ectoderm near the streak and surrounding Hensen's node, regions that recent fate mapping studies suggest that primarily destined to give rise to neurectoderm. At the definitive streak stage (Hamburger and Hamilton stage 4) the chick embryo is especially sensitive to the induction of axial malformations by retinoic acid. Four hours after the treatment of definitive streak embryos with a pulse of retinoic acid the expression of Ghox 2.9 protein is greatly elevated. This ectopic expression occurs in tissues anterior to Hensen's node, including floor plate, notochord, presumptive neural plate and lateral plate mesoderm, but does not occur in the anteriormost region of the embryo. The ectopic induction of Ghox 2.9 is strongest in ectoderm, and weaker in the underlying mesoderm. Endoderm throughout the embryo is unresponsive. At stage 11, Ghox 2.9 is normally expressed at high levels within rhombomere 4 of the developing hindbrain. In retinoic-acid-treated embryos which have developed to this stage, typical rhombomere boundaries are largely absent. Nevertheless, Ghox 2.9 is still expressed as a discrete band, but one that is widened and displaced to a more anterior position.

Changes in the expression of the carbohydrate epitope HNK-1 associated with mesoderm induction in the chick embryo

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 643-655 ◽  
Author(s):  
D.R. Canning ◽  
C.D. Stern
Keyword(s):  
Affinity Purification ◽  
Primitive Streak ◽  
Cell Types ◽  
Staining Intensity ◽  
Mesoderm Induction ◽  
Lateral Plate ◽  
Chick Blastoderm ◽  
Western Blots ◽  
Immunohistochemical Studies ◽  
Related Proteins

We report that a monoclonal antibody, HNK-1, identifies specific regions and cell types during primitive streak formation in the chick blastoderm. Immunohistochemical studies show that the cells of the forming hypoblast are HNK-1 positive from the earliest time at which they can be identified. Some cells of the margin of the blastoderm are also positive. The mesoderm cells of the primitive streak stain strongly with the antibody from the time of their initial appearance. In the epiblast, some cells are positive and some negative at pre-primitive-streak stages, but as the primitive streak develops a gradient of staining intensity is seen within the upper layer, increasing towards the primitive streak. At later stages of development, the notochord and the mesenchyme of the headfold are positive, while the rest of the mesoderm (lateral plate) no longer expresses HNK-1 immunoreactivity. This antibody therefore reveals changes associated with mesodermal induction: before induction, it recognizes the ‘inducing’ tissue (the hypoblast) and reveals a mosaic pattern in the responding tissue (the epiblast); after primitive streak formation, the mesoderm of the primitive streak that results from the inductive interactions expresses the epitope strongly. Affinity purification of HNK-1-related proteins in various tissues was carried out, followed by SDS-PAGE to identify them. The hypoblast, mesoderm and epiblast of gastrulating chick embryos have some HNK-1-related proteins in common, while others are unique to specific tissues. Attempts have been made to identify these proteins using Western blots and antibodies known to recognize HNK-1-related molecules, but none of the antibodies used identify the bands unique to any of the tissues studied. We conclude that these proteins may be novel members of the HNK-1/L2 family, and that they may have a role in cell interactions during early development.

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