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.

The origin and movement of nephrogenic cells in the chick embryo as determined by radioautographic mapping

Development ◽  
1970 ◽  
Vol 24 (2) ◽  
pp. 367-380
Author(s):  
Glenn C. Rosenquist
Keyword(s):  
Chick Embryo ◽  
Tritiated Thymidine ◽  
Anterior Part ◽  
The Other ◽  
Lateral Plate ◽  
Intermediate Mesoderm ◽  
Somite Stage ◽  
Stage Of Development ◽  
Stage Embryo ◽  
Area Pellucida

The origin of the presumptive nephrogenic cells in the epiblast of the chick embryo was traced by radioautographic analysis of the movements of tritiated thymidine-labelled grafts excised from medium-streak to 5-somite stage embryos and transplanted to epiblast, streak, and the endoderm-mesoderm layer of similarly staged recipient embryos. The nephrogenic cells originate near the area pellucida margin of the medium-streak-stage embryo, migrate toward the streak, and are invaginated about one-third to one-half the distance from the anterior to the posterior end of the streak, between the definitive-streak and I - to 4-somite stages. Their route into mesoderm is along a relatively narrow pathway between the cells migrating to the paraxial or presomite mesoderm on one side, and those destined for the proximal limbs of the lateral plate on the other. The cells which will form the anterior part of the intermediate mesoderm are the most medially placed cells in epiblast, reach the streak at an earlier stage of development, and are the first nephrogenic cells to migrate into mesoderm. After about the 17– to 19-somite stage, cells from this group which have formed the pronephric cord or duct begin to move posteriorly in relation to the rest of the intermediate mesoderm, toward the future cloaca. The last nephrogenic cells to leave epiblast and enter the streak and mesoderm are those destined for the posterior end of the intermediate mesoderm. This group of cells surrounds the posteriorly migrating pronephric (Wolffian) duct and differentiates into mesonephros.

scholarly journals Distinct requirements for extra-embryonic and embryonic bone morphogenetic protein 4 in the formation of the node and primitive streak and coordination of left-right asymmetry in the mouse

Development ◽  
2002 ◽  
Vol 129 (20) ◽  
pp. 4685-4696 ◽  
Author(s):  
Takeshi Fujiwara ◽  
Deborah B. Dehart ◽  
Kathleen K. Sulik ◽  
Brigid L. M. Hogan
Keyword(s):  
Chick Embryo ◽  
Bone Morphogenetic Protein ◽  
Primitive Streak ◽  
Positional Information ◽  
Bone Morphogenetic Protein 4 ◽  
Lateral Plate ◽  
Morphogenetic Protein ◽  
Normal Node ◽  
Bmp4 Expression ◽  
Left Right Asymmetry

In the mouse and chick embryo, the node plays a central role in generating left-right (LR) positional information. Using several different strategies, we provide evidence in the mouse that bone morphogenetic protein 4 (Bmp4) is required independently in two different sites for node morphogenesis and for LR patterning. Bmp4 expression in the trophoblast-derived extra-embryonic ectoderm is essential for the normal formation of the node and primitive streak. However, tetraploid chimera analysis demonstrates that Bmp4 made in epiblast-derived tissues is required for robust LR patterning, even when normal node morphology is restored. In the absence of embryonic Bmp4, the expression of left-side determinants such as Nodal and Lefty2 is absent in the left lateral plate mesoderm (LPM). Noggin-mediated inhibition of Bmp activity in cultured wild-type embryos results in suppression of Nodal expression in the LPM. Thus, unlike previous models proposed in the chick embryo in which Bmp4 suppresses left-sided gene expression, our results suggest that Bmp acts as a positive facilitator of the left-sided molecular cascade and is required for Nodal induction and maintenance in the left LPM.

Regulation of midline development by antagonism of lefty and nodal signaling

Development ◽  
1999 ◽  
Vol 126 (14) ◽  
pp. 3253-3262 ◽  
Author(s):  
B.W. Bisgrove ◽  
J.J. Essner ◽  
H.J. Yost
Keyword(s):  
Expression Patterns ◽  
Ectopic Expression ◽  
Bilateral Symmetry ◽  
Expression Domain ◽  
Lateral Plate ◽  
Altered Expression ◽  
Left Right Asymmetry ◽  
Midline Development ◽  
Additional Role ◽  
Pitx2 Expression

The embryonic midline is crucial for the development of embryonic pattern including bilateral symmetry and left-right asymmetry. In zebrafish, lefty1 (lft1) and lefty2 (lft2) have distinct midline expression domains along the anteroposterior axis that overlap with the expression patterns of the nodal-related genes cyclops and squint. Altered expression patterns of lft1 and lft2 in zebrafish mutants that affect midline development suggests different upstream pathways regulate each expression domain. Ectopic expression analysis demonstrates that a balance of lefty and cyclops signaling is required for normal mesendoderm patterning and goosecoid, no tail and pitx2 expression. In late somite-stage embryos, lft1 and lft2 are expressed asymmetrically in the left diencephalon and left lateral plate respectively, suggesting an additional role in laterality development. A model is proposed by which the vertebrate midline, and thus bilateral symmetry, is established and maintained by antagonistic interactions among co-expressed members of the lefty and nodal subfamilies of TGF-beta signaling molecules.

The distribution of endogenous retinoic acid in the chick embryo: implications for developmental mechanisms

Development ◽  
1998 ◽  
Vol 125 (21) ◽  
pp. 4133-4144 ◽  
Author(s):  
M. Maden ◽  
E. Sonneveld ◽  
P.T. van der Saag ◽  
E. Gale
Keyword(s):  
Retinoic Acid ◽  
Chick Embryo ◽  
Neural Tube ◽  
Cell System ◽  
Limb Bud ◽  
Lateral Plate ◽  
F9 Cells ◽  
Chick Embryogenesis ◽  
Wide Range ◽  
Very High

The aim of these experiments was to determine the endogenous distribution of retinoic acid (RA) across a wide range of embryonic stages in the chick embryo. By high pressure liquid chromatography, it was revealed that didehydroRA is the most prevalent retinoic acid in the chick embryo and that the tissues of the stage 24 embryo differed widely in their total RA content (didehydroRA + all-trans-RA). Some tissues such as the heart had very little RA and some such as the neural tube had very high levels, the total variation between these two being 29-fold. We showed that these tissues also synthesised RA and released it into the medium, thus validating the use of the F9 reporter cell system for further analyses of younger staged embryos. With these F9 cells, we showed that, at stage 4, the posterior end of the embryo had barely detectably higher levels of RA than the anterior end, but that a significant level of RA generation was detected as soon as somitogenesis began. Then a sharp on/off boundary of RA was present at the level of the first somite. We could find no evidence for a posterior-to-anterior gradient of RA. Throughout further development, various consistent observations were made: the developing brain did not generate RA, but the spinal part of the neural tube generated it at very high levels so there must be a sharp on/off boundary in the region of the hindbrain/spinal cord junction; the mesenchyme surrounding the hindbrain generated RA whereas the hindbrain itself did not; there was a variation in RA levels from the midline outwards with the highest levels of RA in the spinal neural tube followed by lower levels in the somites followed by lower levels in the lateral plate; the posterior half of the limb bud generated higher levels than the anterior half. With these observations, we were able to draw maps of endogenous RA throughout these early stages of chick embryogenesis and the developmental implications of these results are discussed.

The origin and movements of the hepatogenic cells in the chick embryo as determined by radioautographic mapping

Development ◽  
1971 ◽  
Vol 25 (1) ◽  
pp. 97-113
Author(s):  
Glenn C. Rosenquist
Keyword(s):  
Chick Embryo ◽  
Developmental Stage ◽  
Primitive Streak ◽  
Limb Bud ◽  
Chick Embryos ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Somite Stage ◽  
Definition Of ◽  
Exact Definition

The origin of the prehepatic cells was determined by tracing the movements of [3H]thymidine-labelled grafts excised from medium-streak to 4-somite stage chick embryos and transplanted to the epiblast, streak and endoderm-mesoderm layer of similarly staged recipient embryos. Although exact definition of prehepatic areas was not possible because of the small number of grafts placed at each developmental stage, the study showed in general that at the medium-streak stage, the prehepatic endoderm cells are in the anterior third of the primitive streak; they shortly begin to migrate anteriorly and laterally into the endoderm layer ventral to the precardiac areas of mesoderm. They are in the yolk-sac endoderm at the 2–4-somite stage, and by the 15–17-somite stage are clustered at the anterior intestinal portal. At the 26-somite to early limb-bud stages, the anterior and posterior liver diverticula have formed from these endoderm cells, and some of the branches of the diverticula may have reached the prehepatic mesenchyme, where the two tissues have begun to form cords and sinuses. At the medium-streak stage, the prehepatic mesoderm is located slightly more than halfway from the anterior to the posterior end of the primitive streak. From this position it migrates anteriorly and laterally into the lateral plate mesoderm, and from the head-process to the 2–4-somite stage it is situated posterior to the prehepatic endoderm and posterior and lateral to the heart-forming portion of the splanchnic layer. By the 15–17-somite stage the prehepatic mesoderm has reached a position in the splanchnic layer of mesoderm which forms the dorsolateral wall of the sinus venosus. By the 26-somite to early limb-bud stage the hepatic diverticula have joined with the hepatic mesenchyme to form the rudimentary cords and sinuses of the liver.

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