Induction of primitive streak and Hensen's node by the posterior marginal zone in the early chick embryo

Development ◽  
1998 ◽  
Vol 125 (17) ◽  
pp. 3521-3534 ◽  
Author(s):  
R.F. Bachvarova ◽  
I. Skromne ◽  
C.D. Stern
Keyword(s):  
Chick Embryo ◽  
Marginal Zone ◽  
Lower Layer ◽  
Primitive Streak ◽  
Normal Embryo ◽  
Anterior Pole ◽  
Posterior Edge ◽  
Amphibian Embryo ◽  
Midline Cells ◽  
Marginal Zones

In the preprimitive streak chick embryo, the search for a region capable of inducing the organizer, equivalent to the Nieuwkoop Center of the amphibian embryo, has focused on Koller's sickle, the hypoblast and the posterior marginal zone. However, no clear evidence for induction of an organizer without contribution from the inducing tissue has been provided for any of these structures. We have used DiI/DiO labeling to establish the fate of midline cells in and around Koller's sickle in the normal embryo. In the epiblast, the boundary between cells that contribute to the streak and those that do not lies at the posterior edge of Koller's sickle, except at stage X when it lies slightly more posteriorly in the epiblast. Hypoblast and endoblast (a second lower layer formed under the streak) have distinct origins in the lower layer, and goosecoid expression distinguishes between them. We then used anterior halves of chick prestreak embryos as recipients for grafts of quail posterior marginal zone; quail cells can be identified subsequently with a quail-specific antibody. Anterior halves alone usually formed a streak, most often from the posterior edge. Quail posterior marginal zones without Koller's sickle were grafted to the anterior side of anterior halves. These grafts were able to increase significantly the frequency of streaks arising from the anterior pole of stage X-XI anterior halves without contributing to the streak or node. Stage XII anterior halves no longer responded. A goosecoid-expressing hypoblast did not form under the induced streak, indicating that it is not required for streak formation. We conclude that the marginal zone posterior to Koller's sickle can induce a streak and node, without contributing cells to the induced streak.

Interactions between Wnt and Vg1 signalling pathways initiate primitive streak formation in the chick embryo

Development ◽  
2001 ◽  
Vol 128 (15) ◽  
pp. 2915-2927 ◽  
Author(s):  
Isaac Skromne ◽  
Claudio D. Stern
Keyword(s):  
Chick Embryo ◽  
Marginal Zone ◽  
Primitive Streak ◽  
Embryonic Axis ◽  
Normal Embryo ◽  
Signalling Pathways ◽  
Axis Formation ◽  
Distinct Region ◽  
Wnt Pathways ◽  
Area Pellucida

The posterior marginal zone (PMZ) of the chick embryo has Nieuwkoop centre-like properties: when transplanted to another part of the marginal zone, it induces a complete embryonic axis, without making a cellular contribution to the induced structures. However, when the PMZ is removed, the embryo can initiate axis formation from another part of the remaining marginal zone. Chick Vg1 can mimic the axis-inducing ability of the PMZ, but only when misexpressed somewhere within the marginal zone. We have investigated the properties that define the marginal zone as a distinct region. We show that the competence of the marginal zone to initiate ectopic primitive streak formation in response to cVg1 is dependent on Wnt activity. First, within the Wnt family, only Wnt8C is expressed in the marginal zone, in a gradient decreasing from posterior to anterior. Second, misexpression of Wnt1 in the area pellucida enables this region to form a primitive streak in response to cVg1. Third, the Wnt antagonists Crescent and Dkk-1 block the primitive streak-inducing ability of cVg1 in the marginal zone. These findings suggest that Wnt activity defines the marginal zone and allows cVg1 to induce an axis. We also present data suggesting some additional complexity: first, the Vg1 and Wnt pathways appear to regulate the expression of downstream components of each other’s pathway; and second, misexpression of different Wnt antagonists suggests that different classes of Wnts may cooperate with each other to regulate axis formation in the normal embryo.

scholarly journals Avian marginal zone cells function as primitive streak inducers only after their migration into the hypoblast

Development ◽  
1994 ◽  
Vol 120 (9) ◽  
pp. 2501-2509 ◽  
Author(s):  
H. Eyal-Giladi ◽  
T. Lotan ◽  
T. Levin ◽  
O. Avner ◽  
J. Hochman
Keyword(s):  
Incubation Medium ◽  
Marginal Zone ◽  
Electrophoretic Pattern ◽  
Primitive Streak ◽  
Electrophoretic Analysis ◽  
Avian Embryo ◽  
Central Disc ◽  
Induction Process ◽  
Marginal Zones

Hypoblast cells of posterior marginal zone origin have been shown previously to be the inducers of primitive streak in the avian embryo. Here we checked: (1) whether the above cells acquire their inductivity while still whithin the marginal zone; (2) can inductivity be found in supernatants of defined blastodermic regions; (3) can differences in the electrophoretic pattern be shown between inducing and non-inducing tissue fragments and their conditioned media, which might give a clue as to what the inductive substance is. The following observations were made: 1. (a) Stage X chick posterior marginal zone cells prior to their migration into the hypoblast do not induce a primitive streak, when applied to a stage XIII competent epiblast central disc. (b) A posterior marginal zone fragment, when applied to an epiblast central disc, even after being preincubated for up to 9 hours in vitro, is still non-inductive. (c) Mechanically fragmented stage X posterior marginal zones when applied as a layer to epiblast central discs are non-inductive. (d) Hypoblastic tissue in strip form induces a primitive streak. 2. Competent stage XIII epiblast central discs (chick) were incubated for 2 hours in supernatants of stage XIII epiblasts or hypoblasts. Whereas no inductive effect was exerted by the epiblast supernatant, primitive streaks developed in about 50% of the epiblast central discs incubated in the hypoblast supernatant. 3. Electrophoretic analysis (quails) reveals a protein of 28x10-3 Mr that is enriched in both hypoblastic tissue and its incubation medium and not in the epiblast + marginal zone + area opaca and their incubation medium. These findings suggest a possible correlation between this protein and the induction process.

The marginal zone and its contribution to the hypoblast and primitive streak of the chick embryo

Development ◽  
1990 ◽  
Vol 109 (3) ◽  
pp. 667-682 ◽  
Author(s):  
C.D. Stern
Keyword(s):  
Chick Embryo ◽  
Marginal Zone ◽  
Primitive Streak ◽  
Time Lapse ◽  
Study Time ◽  
Fate Mapping ◽  
Deep Part ◽  
Germ Layers ◽  
Gut Endoderm ◽  
Transplantation Experiments

The marginal zone of the chick embryo has been shown to play an important role in the formation of the hypoblast and of the primitive streak. In this study, time-lapse filming, fate mapping, ablation and transplantation experiments were combined to study its contribution to these structures. It was found that the deep (endodermal) portion of the posterior marginal zone contributes to the hypoblast and to the junctional endoblast, while the epiblast portion of the same region contributes to the epiblast of the primitive streak and to the definitive (gut) endoderm derived from it. Within the deep part of the posterior marginal zone, a subpopulation of HNK-1-positive cells contributes to the hypoblast. Removal of the deep part of the marginal zone prevents regeneration of the hypoblast but not the formation of a primitive streak. Removal of both layers of the marginal zone leads to a primitive streak of abnormal morphology but mesendodermal cells nevertheless differentiate. These results show that the two main properties of the posterior marginal zone (contributing to the hypoblast and controlling the site of primitive streak formation) are separable, and reside in different germ layers. This conclusion does not support the idea that the influence of the posterior marginal zone on the development of axial structures is due to it being the source of secondary hypoblast cells.

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 A novel role for the extraembryonic area opaca in positioning the primitive streak of the early chick embryo

2021 ◽  
Author(s):  
Hyung Chul Lee ◽  
Claudio D Stern
Keyword(s):  
Chick Embryo ◽  
Early Development ◽  
Marginal Zone ◽  
Outer Region ◽  
Primitive Streak ◽  
Support Functions ◽  
Anterior Half ◽  
Embryonic Polarity ◽  
Classical Studies ◽  
Area Pellucida

Classical studies have established that the marginal zone, a ring of extraembryonic epiblast immediately surrounding the embryonic epiblast (area pellucida) of the chick embryo is important in setting embryonic polarity by positioning the primitive streak, the site of gastrulation. The more external extraembryonic region (area opaca) was only thought to have nutritive and support functions. Using experimental embryology approaches, this study reveals three separable functions for this outer region: first, juxtaposition of the area opaca directly onto the area pellucida induces a new marginal zone from the latter; this induced domain is entirely posterior in character. Second, ablation and grafting experiments using an isolated anterior half of the blastoderm and pieces of area opaca suggest that the area opaca can influence the polarity of the adjacent marginal zone. Finally, we show that the loss of the ability of such isolated anterior half-embryos to regulate (re-establish polarity spontaneously) at the early primitive streak stage can be rescued by replacing the area opaca by one from a younger stage. These results uncover new roles of chick extraembryonic tissues in early development.

Anti-apoptotic role of Sonic hedgehog protein at the early stages of nervous system organogenesis

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 4011-4020 ◽  
Author(s):  
Jean-Baptiste Charrier ◽  
Françoise Lapointe ◽  
Nicole M. Le Douarin ◽  
Marie-Aimée Teillet
Keyword(s):  
Cell Death ◽  
Nervous System ◽  
Chick Embryo ◽  
Sonic Hedgehog ◽  
Neural Tube ◽  
Primitive Streak ◽  
Embryo Cell ◽  
Floor Plate ◽  
Cell Death Program ◽  
Midline Cells

In vertebrates the neural tube, like most of the embryonic organs, shows discreet areas of programmed cell death at several stages during development. In the chick embryo, cell death is dramatically increased in the developing nervous system and other tissues when the midline cells, notochord and floor plate, are prevented from forming by excision of the axial-paraxial hinge (APH), i.e. caudal Hensen’s node and rostral primitive streak, at the 6-somite stage (Charrier, J. B., Teillet, M.-A., Lapointe, F. and Le Douarin, N. M. (1999). Development126, 4771-4783). In this paper we demonstrate that one day after APH excision, when dramatic apoptosis is already present in the neural tube, the latter can be rescued from death by grafting a notochord or a floor plate fragment in its vicinity. The neural tube can also be recovered by transplanting it into a stage-matched chick embryo having one of these structures. In addition, cells engineered to produce Sonic hedgehog protein (SHH) can mimic the effect of the notochord and floor plate cells in in situ grafts and transplantation experiments. SHH can thus counteract a built-in cell death program and thereby contribute to organ morphogenesis, in particular in the central nervous system.

Sign in / Sign up

Export Citation Format

Share Document