The posterior section of the chick's area pellucida and its involvement in hypoblast and primitive streak formation

Development ◽  
1992 ◽  
Vol 116 (3) ◽  
pp. 819-830 ◽  
Author(s):  
H. Eyal-Giladi ◽  
A. Debby ◽  
N. Harel
Keyword(s):  
Distribution Pattern ◽  
Marginal Zone ◽  
Primitive Streak ◽  
Fluorescent Dye ◽  
Narrow Strip ◽  
Posterior Section ◽  
Area Pellucida

Posterior marginal zone sections with or without Koller's sickle were cut out of stage X, XI and XII E.G&K blastoderms, labelled with the fluorescent dye rhodamine-dextran-lysine (RDL) and returned to their original location. In control experiments, a similar lateral section of the marginal zone was identically treated. Different blastoderms were incubated at 37°C for different periods and were fixed after reaching stages from XII E.G&K to 4 H&H. The conclusions drawn from the analysis of the distribution pattern of the labelled cells in the serially sectioned blastoderms concern the cellular contributions to both the forming hypoblast and the forming primitive streak. Koller's sickle and the marginal zone behind it were found to contribute all the centrally located cells of the growing hypoblast. The lengthening pregastrulation PS (until stage 3+ H&H) was found to be entirely composed of epiblastic cells that at stage X were located in a narrow strip anterior to Koller's sickle. A model is proposed to integrate the results spatially and temporally.

Misexpression of chick Vg1 in the marginal zone induces primitive streak formation

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5127-5138 ◽  
Author(s):  
S.B. Shah ◽  
I. Skromne ◽  
C.R. Hume ◽  
D.S. Kessler ◽  
K.J. Lee ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Primitive Streak ◽  
Axis Formation ◽  
Mesoderm Induction ◽  
Cell Fates ◽  
Signalling Molecules ◽  
Posterior Area ◽  
Area Pellucida

In the chick embryo, the primitive streak is the first axial structure to develop. The initiation of primitive streak formation in the posterior area pellucida is influenced by the adjacent posterior marginal zone (PMZ). We show here that chick Vg1 (cVg1), a member of the TGFbeta family of signalling molecules whose homolog in Xenopus is implicated in mesoderm induction, is expressed in the PMZ of prestreak embryos. Ectopic expression of cVg1 protein in the marginal zone chick blastoderms directs the formation of a secondary primitive streak, which subsequently develops into an ectopic embryo. We have used cell marking techniques to show that cells that contribute to the ectopic primitive streak change fate, acquiring two distinct properties of primitive streak cells, defined by gene expression and cell movements. Furthermore, naive epiblast explants exposed to cVg1 protein in vitro acquire axial mesodermal properties. Together, these results show that cVg1 can mediate ectopic axis formation in the chick by inducing new cell fates and they permit the analysis of distinct events that occur during primitive streak formation.

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.

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 Marginal zone cells—the primitive streak-inducing component of the primary hypoblast in the chick

Development ◽  
1979 ◽  
Vol 52 (1) ◽  
pp. 79-88
Author(s):  
Yehudit Azar ◽  
Hefzibah Eyal-Giladi
Keyword(s):  
Marginal Zone ◽  
Primitive Streak ◽  
Type Iv ◽  
Area Pellucida

(1) Removal of both the area opaca and the marginal zone of the area pellucida from ablastoderm stripped of its hypoblast (type-lV operation) prevents the regeneration of a normally functioning primary hypoblast. (2) Stage-XIIl E.G & K blastoderms (prior to the appearance of PS) after a type-lV operation do not form a primitive streak. (3) In older type-lV operated blastoderms in which the primitive streak has already begun to appear, the regeneration of a non-functional hypoblast did not support the normal maturation of the primitive streak, and in many cases the already existing rudimentary streak was absorbed. (4) Type-IV operated blastoderms from stage 3+ H & H and on developed normally. (5) It is concluded that the cellular contribution of the marginal zone to the primary hypoblast is instrumental in the latter's capacity to induce a PS.

Primordial germ cells in normal and transected duck blastoderms

Development ◽  
1968 ◽  
Vol 20 (3) ◽  
pp. 247-260
Author(s):  
Teresa Rogulska
Keyword(s):  
Chick Embryo ◽  
Blood Vessels ◽  
Germ Cells ◽  
Anterior Part ◽  
Primordial Germ Cells ◽  
Primitive Streak ◽  
Experimental Investigations ◽  
Suggestive Evidence ◽  
Area Pellucida

Suggestive evidence for the extragonadal origin of germ cells in birds was first presented by Swift (1914), who described primordial germ cells in the chick embryo at as early a stage as the primitive streak. According to Swift, primordial germ cells are originally located extra-embryonically in the anterior part of the blastoderm and occupy a crescent-shaped region (‘germinal crescent’) on the boundary between area opaca and area pellucida. Swift also found that primordial germ cells later enter into the blood vessels, circulate together with the blood throughout the whole blastoderm and finally penetrate into the genital ridges, where they become definitive germ cells. Swift's views have been confirmed in numerous descriptive and experimental investigations. Among the latter, the publications of Willier (1937), Simon (1960) and Dubois (1964a, b, 1965a, b, 1966) merit special attention. Dubois finally proved that the genital ridges exert a strong chemotactic influence on the primordial germ cells.

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.

scholarly journals Vasculogenesis in the early quail blastodisc as studied with a monoclonal antibody recognizing endothelial cells

Development ◽  
1987 ◽  
Vol 100 (2) ◽  
pp. 339-349 ◽  
Author(s):  
L. Pardanaud ◽  
C. Altmann ◽  
P. Kitos ◽  
F. Dieterlen-Lievre ◽  
C.A. Buck
Keyword(s):  
Monoclonal Antibody ◽  
Endothelial Cells ◽  
Single Cells ◽  
Primitive Streak ◽  
Vascular Network ◽  
Vascular Tree ◽  
Somite Stage ◽  
Area Vasculosa ◽  
Haemopoietic Cells ◽  
Area Pellucida

QH1, a monoclonal antibody that recognizes quail endothelial and haemopoietic cells, was applied to quail blastodiscs in toto, in order to analyse by immunofluorescence the emergence of the vascular tree. The first endothelial cells were detected in the area opaca at the headfold stage and in the area pellucida at the 1-somite stage. Single cells then interconnected progressively, especially in the anterior intestinal portal and along the somites building up the linings of the heart and dorsal aortas. This study demonstrates that endothelial cells differentiate as single entities 4 h earlier in development than hitherto detected and that the vascular network forms secondarily. The horseshoe shape of the extraembryonic area vasculosa is also a secondary acquisition. A nonvascularized area persists until later (at least the 14-somite stage) in the region of the regressing primitive streak.

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.

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.

Cwnt-8C: a novel Wnt gene with a potential role in primitive streak formation and hindbrain organization

Development ◽  
1993 ◽  
Vol 119 (4) ◽  
pp. 1147-1160 ◽  
Author(s):  
C.R. Hume ◽  
J. Dodd
Keyword(s):  
Gene Family ◽  
Potential Role ◽  
Marginal Zone ◽  
Cell Signalling ◽  
Primitive Streak ◽  
Axis Formation ◽  
Restricted Domain ◽  
Signalling Molecules ◽  
Wnt Proteins ◽  
Chick Embryogenesis

To begin to examine the possibility that Wnt proteins act as cell signalling molecules during chick embryogenesis, PCR was used to identify Wnt genes expressed in Hensen's node. We have identified a novel member of the Wnt gene family, Cwnt-8C, which is expressed prior to gastrulation in the posterior marginal zone, the primitive streak and Hensen's node. Injection of Cwnt-8C mRNA into Xenopus embryos caused axis duplication and dorsalization of mesodermal tissues. During neurulation, Cwnt-8C is expressed transiently in a restricted domain of the prospective hindbrain neurectoderm that will give rise to rhombomere 4. This domain is defined prior to the formation of rhombomere boundaries and also precedes the up-regulation and restriction of expression of Hox B1 in the same region. Thus, Cwnt-8C is potentially involved in the regulation of axis formation and hindbrain patterning.

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