A fate map of superficial and deep circumblastoporal cells in the early gastrula of Pleurodeles waltl

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 135-146 ◽  
Author(s):  
M. Delarue ◽  
S. Sanchez ◽  
K.E. Johnson ◽  
T. Darribere ◽  
J.C. Boucaut
Keyword(s):  
Marginal Zone ◽  
Cell Lineage ◽  
Tail Bud ◽  
Fate Map ◽  
Pleurodeles Waltl ◽  
Early Gastrula

We have determined the fate of presumptive mesodermal cells in the early Pleurodeles waltl gastrula. We labeled all cells in a gastrula with RLDx cell lineage tracer and superficial cells with 125I and then grafted small pieces of the marginal zone orthotopically into unlabeled host embryos. Labeled progeny were identified in sectioned embryos at the tail bud stage. The use of double-labeled grafts allowed us to study the relative contributions by superficial and deep cells to different derivatives. We found that the presumptive regions are generally distributed according to classical fate maps for urodeles but that the boundaries between presumptive regions are indistinct, due to extensive intermingling between cells at the edges of grafted regions. We have shown that there is a high dorsal to low ventral gradient of mixing between superficial and deep cells.

Experimental analysis of the extension of the dorsal marginal zone in Pleurodeles waltl gastrulae

Development ◽  
1987 ◽  
Vol 100 (1) ◽  
pp. 147-161 ◽  
Author(s):  
D.L. Shi ◽  
M. Delarue ◽  
T. Darribere ◽  
J.F. Riou ◽  
J.C. Boucaut
Keyword(s):  
Electron Microscopy ◽  
Marginal Zone ◽  
Cell Lineage ◽  
Single Layer ◽  
Gastrula Stage ◽  
Animal Pole ◽  
A Cell ◽  
Pleurodeles Waltl ◽  
Scanning Electron

The capacity for extension of the dorsal marginal zone (DMZ) in Pleurodeles waltl gastrulae was studied by scanning electron microscopy and grafting experiments. At the onset of gastrulation, the cells of the animal pole (AP) undergo important changes in shape and form a single layer. As gastrulation proceeds, the arrangement of cells also changes in the noninvoluted DMZ: radial intercalation leads to a single layer of cells. Grafting experiments involving either AP or DMZ explants were performed using a cell lineage tracer. When rotated 90 degrees or 180 degrees, grafted DMZ explants were able to involute normally and there was extension according to the animal-vegetal axis of the host. In contrast, neither single nor bilayered explants from AP involutes completely, and neither extends when grafted in place of the DMZ. Furthermore, when inside of the host, these AP grafts curl up and inhibit the closure of the blastopore. Once transplanted to the AP region, the DMZ showed no obvious autonomous extension. DMZs cultured in vitro showed little extension and this only from the late gastrula stage onward. Removal of blastocoel roof blocked involution to a varied extent, depending on the developmental stage of the embryos. From these results, it is argued that differences could well exist in the mechanism of gastrulation between anuran and urodele embryos. That migrating mesodermal cells play a major role in urodele gastrulation is discussed.

Blastomere derivation and domains of gene expression in the Spemann Organizer of Xenopus laevis

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3505-3518 ◽  
Author(s):  
M.A. Vodicka ◽  
J.C. Gerhart
Keyword(s):  
Gene Expression ◽  
Marginal Zone ◽  
Early Stage ◽  
Fate Map ◽  
Early Cleavage ◽  
Spemann Organizer ◽  
Spemann's Organizer ◽  
Cell Embryo ◽  
Early Gastrula

Spemann's Organizer, located in the dorsal marginal zone of the amphibian gastrula, induces and differentiates dorsal axial structures characteristic of this and other vertebrates. To trace the cellular origins of the Xenopus Organizer, we labelled dorsal blastomeres of three of the four tiers (A, B and C) of the 32-cell embryo with green, red and blue fluorescent lineage tracers. A strong vegetalward displacement of labelled clones occurs between the late blastula and early gastrula stages but clones mix only slightly at their borders. The typical early gastrula Organizer is composed of approximately 10% A1 progeny in its animalmost region, 70% B1 progeny in the central region, and 20% C1 progeny in vegetal and deep regions. Variability in the composition of the early gastrula Organizer results from variability in the position of early cleavage planes and in pregastrulation movements. As the Organizer involutes during gastrulation, forming dorsal axial mesoderm, clonal boundaries are greatly dispersed by cell intermixing. Within a clone, deep cells are displaced and intermixed more than superficial cells. Variability in the distribution of progeny in the dorsal axial mesoderm of the late gastrula results mostly from variable intermixing of cells during gastrulation. Experiments to perturb later developmental events by molecular or embryonic manipulations at an early stage must take this variability into account along with the majority distributions of the fate map. Within the early gastrula Organizer, the genes Xbra, goosecoid, noggin and xNR3 are expressed differently in the animal-vegetal and superficial-deep dimensions. In situ hybridization and lineage labelling define distinct regions of the dorsal marginal zone. By the end of gastrulation, dorsal axial mesoderm cells derived from the Organizer have altered their expression of the genes Xbra, goosecoid, noggin and xNR3. At a given stage, a cell's position in the embryo rather than its lineage may be more important in determining which genes it will express.

Initiation of mesodermal cell migration and spreading relative to gastrulation in the urodele amphibian Pleurodeles waltl

Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 351-363 ◽  
Author(s):  
D.-L. Shi ◽  
T. Darribere ◽  
K.E. Johnson ◽  
J.-C. Boucaut
Keyword(s):  
Cell Migration ◽  
Marginal Zone ◽  
Gastrula Stage ◽  
Cell Stage ◽  
Animal Pole ◽  
Mesodermal Cell ◽  
Marginal Cells ◽  
Pleurodeles Waltl ◽  
Early Gastrula

We have investigated the autonomous migration of marginal cells and their interactions with extracellular matrix (ECM) located on the inner surface of the blastocoel roof in the urodele amphibian, Pleurodeles waltl, using a novel in vitro migration assay. Animal hemispheres containing equatorial cells removed at different cleavage stages and dorsal marginal zone (DMZ) explants of early gastrula stage were cultured either on fibronectin (FN)-coated or ECM-conditioned substrata. In explanted animal hemispheres, dorsal marginal cells showed autonomous migration on FN-coated substratum at the same time as the onset of gastrulation in control embryos. They acquired this capacity at least at the 32-cell stage, whereas lateral and ventral marginal cells acquired it after the 64-cell stage. DMZ outgrowths of early gastrula stage exhibited autonomous spreading on both substrata. In addition, we showed that they spread preferentially toward the animal pole when deposited on substratum conditioned by the dorsal roof of the blastocoel. By culturing dissociated marginal cells on ECM- conditioned substratum, we also found that increased spreading capacity of marginal cells was related to the initiation of their migration. A comparative study of the migration of marginal cells in ultraviolet (u.v.)-irradiated and normal embryos was also made. The results indicate that dorsal marginal cell migration was absent or dramatically reduced by u.v.-irradiation. These results suggest that the differential acquisition in the spreading capacity both in timing and in intensity around the marginal zone was correlated with the sequential involution of mesodermal cells in the course of gastrulation.

Normal fates and states of specification of different regions in the axolotl gastrula

Development ◽  
1985 ◽  
Vol 86 (1) ◽  
pp. 247-269
Author(s):  
J. Herman Cleine ◽  
Jonathan M. W. Slack
Keyword(s):  
Marginal Zone ◽  
Culture Conditions ◽  
Early Embryo ◽  
Ambystoma Mexicanum ◽  
Specific Marker ◽  
Fate Map ◽  
Animal Pole ◽  
Glycoprotein Synthesis ◽  
Early Gastrula

A fate map was constructed for four regions of the early gastrula of Ambystoma mexicanum using orthotopic grafts from donors labelled with FLDx (fluoresceinated-lysinated-dextran). The region around the animal pole gave rise to epidermis only and did not include prospective neural plate. The dorsal marginal zone contributed to cephalic endoderm and to the whole length of the axial mesoderm (notochord and somites), the lateral marginal zone to lateroventral and somitic mesoderm, and the ventral marginal zone to lateroventral mesoderm. It was found that the dorsal marginal zone contributed relatively more to the anterior regions of the mesodermal mantle and the ventral marginal zone more to its posterior parts. The same regions of the gastrula and also vegetal yolky tissue were cultured as explants and labelled with tritiated mannose. Their glycoprotein synthesis pattern was compared to those of the neurula tissues to which they contribute in vivo. Animal pole explants synthesized large amounts of the epidermis-specific marker epimucin. Dorsal marginal zone explants did not synthesize epimucin but did make amounts of S2 and S6 indicative of mesoderm, as well as the notochord-specific markers S2·2 and S3·2. Lateral marginal zone explants showed the same pattern as the dorsal marginal zone including the two notochord-specific markers, although they do not contribute to notochord in vivo. Ventral marginal zone explants were more variable in their behaviour. Yolky tissue from the vegetal hemisphere of the gastrula or the archenteron floor of the neurula synthesized mainly polydisperse material of high molecular weight rather than discrete glycoproteins. The results indicate that at the early gastrula stage states of specification exist which correspond to the three germ layers, ecto-, meso- and endoderm. The ectodermal specification of animal pole explants is quite robust and cannot easily be changed by variation of the culture conditions. However treatment with a concentrated pellet of vegetalizing factor does induce a change to mesodermal specification, which is clearly detectable in the pattern of glycoprotein synthesis. Similar inductive interactions between different regions of the early embryo are thought to occur during normal development.

Expression of N-CAM precedes neural induction in Pleurodeles waltl (urodele, amphibian)

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 675-683 ◽  
Author(s):  
J.P. Saint-Jeannet ◽  
F. Foulquier ◽  
C. Goridis ◽  
A.M. Duprat
Keyword(s):  
Monoclonal Antibody ◽  
Nervous System ◽  
Xenopus Laevis ◽  
Neural Induction ◽  
Gastrula Stage ◽  
Pleurodeles Waltl ◽  
Early Gastrula

The appearance and localization of N-CAM during neural induction were studied in Pleurodeles waltl embryos and compared with recent contradictory results reported in Xenopus laevis. A monoclonal antibody raised against mouse N-CAM was used. In the nervous system of Pleurodeles, it recognized two glycoproteins of 180 and 140×10(3) M(r) which are the Pleurodeles equivalent of N-CAM-180 and -140. Using this probe for immunohistochemistry and immunocytochemistry, we showed that N-CAM was already expressed in presumptive ectoderm at the early gastrula stage. In late gastrula embryos, a slight increase in staining was observed in the neurectoderm, whereas the labelling persisted in the noninduced ectoderm. When induced ectodermal cells were isolated at the late gastrula stage and cultured in vitro up to 14 days, a faint polarized labelling of cells was observed initially. During differentiation, the staining increased and became progressively restricted to differentiating neurons.

Structure and developmental tendency of the dorsal marginal zone in the early amphibian gastrula

Development ◽  
1971 ◽  
Vol 25 (2) ◽  
pp. 263-276
Author(s):  
Nobushige Ikushima ◽  
Setsuko Maruyama
Keyword(s):  
Outer Layer ◽  
Marginal Zone ◽  
Kinetic Properties ◽  
Electron Microscopic ◽  
Structural Differences ◽  
Peripheral Surface ◽  
Early Gastrula ◽  
A Share

The peripheral surface of a fertilized, uncleaved egg is subdivided through cleavage and is allotted to constituent cells. This is called the primary surface. In an early morula a constituent cell has two kinds of surfaces: the primary surface, and the secondary surface, which does not participate in forming the periphery of the embryo. Electron-microscopic observations showed structural differences between the two surfaces. When the dorsal marginal zone of an early gastrula of Hynobius nebulosus is excised and immersed in Feldman's solution, the piece can easily be separated into two layers: the outer layer, whose constituent cells are given a share of the primary surface, and the inner layer, whose constituent cells are completely covered only by the secondary surface. Both an explanted piece of the outer layer and an intact double-layered piece show three kinds of movement: spreading, convergence followed by stretching, and spherical thickening. The inner layer is kinetically very inert, showing slight spreading and thickening. An explanted piece of the outer layer differentiates into axial mesodermal structures, while the inner layer does not. When a piece of either the inner or the outer layer is implanted in the blastocoel of another gastrula, it induces deuterencephalic and spino-caudal structures and seems to differentiate into axial mesodermal structures. Differences of kinetic properties and differentiation are considered to result from the fact that the outer layer has the primary surface, while the inner layer does not. Functional effects of the primary surface on the movement of tissues and differentiation are discussed.

The effect of egg rotation on the differentiation of primordial germ cells in Xenopus laevis

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 79-99
Author(s):  
J. H. Cleine ◽  
K. E. Dixon
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Intermediate Zone ◽  
Gastrula Stage ◽  
Tail Bud ◽  
Axis Orientation ◽  
Early Gastrula ◽  
Number Of Cells

Eggs of X. laevis were rotated (sperm entrance point downwards) either through 90° (1×90 embryos) or 180° in two 90° steps (2×90 embryos) at approximately 25–30 min postfertilization after cooling to 13°C. The embryos were kept in their off-axis orientation and cooled until the early gastrula stage. Rotation resulted in relocation of egg constituents with slight changes in the distribution of outer cortical and subcortical components and major changes in inner constituents where the heavy yolk and cytoplasm appeared to reorient as a single coherent unit to maintain their relative positions with respect to gravity. Development of rotated embryos was such that regions of the egg which normally give rise to posterior structures instead developed into anterior structures and vice versa. Germ plasm was displaced in the vegetal-dorsal-animal direction (the direction of rotation) and was segregated into dorsal micromeres and intermediate zone cells in 2×90 embryos and dorsal macromeres and intermediate zone cells in 1×90 embryos. In consequence, at the gastrula stage, cells containing germ plasm were situated closer to the dorsal lip of the blastopore after rotation — in 2×90 gastrulas around and generally above the dorsal lip. Hence, in rotated embryos, the cells containing germ plasm were invaginated earlier during gastrulation and therefore were carried further anteriorly in the endoderm to a mean position anterior to the midpoint of the endoderm. The number of cells containing germ plasm in rotated embryos was not significantly different from that in controls at all stages up to and including tail bud (stage 25). However at stages 46, 48 and 49 the number of primordial germ cells was reduced in 1×90 embryos in one experiment of three and in 2×90 embryos in all experiments. We tested the hypothesis that the decreased number of primordial germ cells in the genital ridges was due to the inability of cells to migrate to the genital ridges from their ectopic location in the endoderm. When anterior endoderm was grafted into posterior endodermal regions the number of primordial germ cells increased slightly or not at all suggesting that the anterior displacement of the cells containing germ plasm was not the only factor responsible for the decreased number of primordial germ cells in rotated embryos. Other possible explanations are discussed.

A spinal cord fate map in the avian embryo: while regressing, Hensen's node lays down the notochord and floor plate thus joining the spinal cord lateral walls

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2599-2610 ◽  
Author(s):  
M. Catala ◽  
M.A. Teillet ◽  
E.M. De Robertis ◽  
M.L. Le Douarin
Keyword(s):  
Spinal Cord ◽  
Primitive Streak ◽  
Floor Plate ◽  
Dorsal Side ◽  
Avian Embryo ◽  
Tail Bud ◽  
Fate Map ◽  
In Ovo ◽  
Somite Stage ◽  
Lateral Walls

The spinal cord of thoracic, lumbar and caudal levels is derived from a region designated as the sinus rhomboidalis in the 6-somite-stage embryo. Using quail/chick grafts performed in ovo, we show the following. (1) The floor plate and notochord derive from a common population of cells, located in Hensen's node, which is equivalent to the chordoneural hinge (CNH) as it was defined at the tail bud stage. (2) The lateral walls and the roof of the neural tube originate caudally and laterally to Hensen's node, during the regression of which the basal plate anlage is bisected by floor plate tissue. (3) Primary and secondary neurulations involve similar morphogenetic movements but, in contrast to primary neurulation, extensive bilateral cell mixing is observed on the dorsal side of the region of secondary neurulation. (4) The posterior midline of the sinus rhomboidalis gives rise to somitic mesoderm and not to spinal cord. Moreover, mesodermal progenitors are spatially arranged along the rest of the primitive streak, more caudal cells giving rise to more lateral embryonic structures. Together with the results reported in our study of tail bud development (Catala, M., Teillet, M.-A. and Le Douarin, N.M. (1995). Mech. Dev. 51, 51–65), these results show that the mechanisms that preside at axial elongation from the 6-somite stage onwards are fundamentally similar during the complete process of neurulation.

A novel Xenopus mix-like gene milk involved in the control of the endomesodermal fates

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2577-2585 ◽  
Author(s):  
V. Ecochard ◽  
C. Cayrol ◽  
S. Rey ◽  
F. Foulquier ◽  
D. Caillol ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Homeobox Gene ◽  
Early Response ◽  
Response Gene ◽  
Mesodermal Cell ◽  
Early Response Gene ◽  
Mesoderm Formation ◽  
Definition Of ◽  
Early Gastrula

Here we describe a novel Xenopus homeobox gene, milk, related by sequence homology and expression pattern to the vegetally expressed Mix.1. As is the case with Mix.1, milk is an immediate early response gene to the mesoderm inducer activin. milk is expressed at the early gastrula stage in the vegetal cells, fated to form endoderm, and in the marginal zone fated to form mesoderm. During gastrulation, expression of milk becomes progressively reduced in the involuting mesodermal cells but is retained in the endoderm, suggesting that it may play a key role in the definition of the endo-mesodermal boundary in the embryo. Overexpression of milk in the marginal zone blocks mesodermal cell involution, represses the expression of several mesodermal genes such as Xbra, goosecoid, Xvent-1 or Xpo and increases the expression of the endodermal gene, endodermin. In the dorsal marginal zone, overexpression of milk leads to a severe late phenotype including the absence of axial structures. Ectopic expression of milk in the animal hemisphere or in ectodermal explants induces a strong expression of endodermin. Taken together, we propose that milk plays a role in the correct patterning of the embryo by repressing mesoderm formation and promoting endoderm identity.

Origin and behaviour of pigment cells in sea urchin embryos

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S42-S43 ◽  
Author(s):  
Tetsuya Kominami
Keyword(s):  
Sea Urchin ◽  
Pigment Cell ◽  
Cell Lineage ◽  
Pigment Cells ◽  
Cleavage Stage ◽  
Fate Map ◽  
Blastula Stage ◽  
Cell Stage ◽  
Stage Embryo ◽  
Founder Cells

Sea urchin pluteus larvae contain dozens of pigment cells in their ectoderm. These pigment cells are the descendants of the veg2 blastomeres of the 60-cell stage embryo. According to the fate map made by Ruffins and Ettensohn, the prospective pigment cells occupy the central region of the vegetal plate. Most of these prospective pigment cells exclusively give rise to pigment cells. Therefore, specification of the pigment cell lineage should occur at some point between the 60-cell and mesenchyme blastula stage. However, the detailed process of the specification of the pigment lineage is unknown.When are pigment cells specified? Are cell interactions necessary for the specification? Do founder cells exist? To answer these questions, I treated embryos with Ca2+-free seawater during the cleavage stage and examined the number of pigment cells observed in pluteus larvae. Treatment at 5.5–8.5 h and especially 7.5–10.5 h postfertilisation markedly reduced the number of pigment cells. The decrease was statistically significant. On the other hand, the treatment at 3.5–6.5 h or 9.5–12.5 h never reduced the number of pigment cells. By examining the frequency of the appearance of embryos whose numbers of pigment cells were less than 20, it was also found that the numbers of pigment cells were frequently in multiples of 4. Embryos having 4, 8, 12, 16 and 20 pigment cells were more frequently observed. Statistics indicated that the frequency of appearance was not random. These results indicated that cell contacts are necessary for the specification of pigment cells and that the specification occurs from 7 to 10 h postfertilisation. The results also suggest that the founder cells, if they exist, divide twice before they differentiate into pigment cells.

Sign in / Sign up

Export Citation Format

Share Document