Dorso-ventral ectodermal compartments and origin of apical ectodermal ridge in developing chick limb

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4547-4556 ◽  
Author(s):  
M. Altabef ◽  
J.D. Clarke ◽  
C. Tickle
Keyword(s):  
Cell Fate ◽  
Apical Ectodermal Ridge ◽  
The Body ◽  
Limb Bud ◽  
Mesodermal Cell ◽  
Cell Lineages ◽  
Compartment Boundary ◽  
Dorsal Ectoderm ◽  
Neural Ectoderm ◽  
Vertebrate Embryos

We wish to understand how limbs are positioned with respect to the dorso-ventral axis of the body in vertebrate embryos, and how different regions of limb bud ectoderm, i.e. dorsal ectoderm, apical ridge and ventral ectoderm, originate. Signals from dorsal and ventral ectoderm control dorso-ventral patterning while the apical ectodermal ridge (AER) controls bud outgrowth and patterning along the proximo-distal axis. We show, using cell-fate tracers, the existence of two distinct ectodermal compartments, dorsal versus ventral, in both presumptive limb and flank of early chick embryos. This organisation of limb ectoderm is the first direct evidence, in vertebrates, of compartments in non-neural ectoderm. Since the apical ridge appears to be confined to this compartment boundary, this positions the limb. The mesoderm, unlike the ectoderm, does not contain two separate dorsal and ventral cell lineages, suggesting that dorsal and ventral ectoderm compartments may be important to ensure appropriate control of mesodermal cell fate. Surprisingly, we also show that cells which form the apical ridge are initially scattered in a wide region of early ectoderm and that both dorsal and ventral ectoderm cells contribute to the apical ridge, intermingling to some extent within it.

The role of tinman, a mesodermal cell fate gene, in axon pathfinding during the development of the transverse nerve in Drosophila

Development ◽  
1994 ◽  
Vol 120 (8) ◽  
pp. 2143-2152 ◽  
Author(s):  
M.G. Gorczyca ◽  
R.W. Phillis ◽  
V. Budnik
Keyword(s):  
Cell Fate ◽  
Glial Cells ◽  
Peripheral Nerves ◽  
The Body ◽  
Axon Pathfinding ◽  
Mesodermal Cell ◽  
Peripheral Neuron ◽  
Neurohemal Organs ◽  
Cns Midline

During the development of peripheral nerves, pioneer axons often navigate over mesodermal tissues. In this paper, we examine the role of the mesodermal cell determination gene tinman on cells that provide pathfinding cues in Drosophila. We focus on a subset of peripheral nerves, the transverse nerves, that innervate abdominal segments. During wildtype embryonic development, the transverse nerve efferents associate with glial cells located on the dorsal aspect of the CNS midline (transverse nerve exit glia). These glial cells have cytoplasmic extensions that prefigure the transverse nerve pathway from the CNS to the body wall musculature prior to transverse nerve formation. Transverse nerve efferents extend along this scaffold to the periphery, where they fasciculate with projections from a peripheral neuron--the LBD. In tinman mutants, the transverse nerve exit glia appear to be missing, and efferent fibers remain stalled at the CNS midline, without forming transverse nerves. In addition, fibers of the LBD neurons are often truncated. These results suggest that the lack of exit glia prevents normal transverse nerve pathfinding. Another prominent defect in tinman is the loss of all dorsal neurohemal organs, FMRFamide-expressing thoracic structures which likely contain the homologs of the transverse nerve exit glia in the thoracic segments. Our results support the hypothesis that the exit glia have a mesodermal origin and that glia play an essential role in determining transverse nerve axon pathways.

XenopusDishevelled signaling regulates both neural and mesodermal convergent extension: parallel forces elongating the body axis

Development ◽  
2001 ◽  
Vol 128 (13) ◽  
pp. 2581-2592 ◽  
Author(s):  
John B. Wallingford ◽  
Richard M. Harland
Keyword(s):  
Wnt Signaling ◽  
Cell Fate ◽  
The Body ◽  
Common Mechanism ◽  
Primary Role ◽  
Convergent Extension ◽  
Mesodermal Cell ◽  
Targeted Expression ◽  
Canonical Wnt ◽  
Different Tissues

During amphibian development, non-canonical Wnt signals regulate the polarity of intercalating dorsal mesoderm cells during convergent extension. Cells of the overlying posterior neural ectoderm engage in similar morphogenetic cell movements. Important differences have been discerned in the cell behaviors associated with neural and mesodermal cell intercalation, raising the possibility that different mechanisms may control intercalations in these two tissues. In this report, targeted expression of mutants of Xenopus Dishevelled (Xdsh) to neural or mesodermal tissues elicited different defects that were consistent with inhibition of either neural or mesodermal convergent extension. Expression of mutant Xdsh also inhibited elongation of neural tissues in vitro in Keller sandwich explants and in vivo in neural plate grafts. Targeted expression of other Wnt signaling antagonists also inhibited neural convergent extension in whole embryos. In situ hybridization indicated that these defects were not due to changes in cell fate. Examination of embryonic phenotypes after inhibition of convergent extension in different tissues reveals a primary role for mesodermal convergent extension in axial elongation, and a role for neural convergent extension as an equalizing force to produce a straight axis. This study demonstrates that non-canonical Wnt signaling is a common mechanism controlling convergent extension in two very different tissues in the Xenopus embryo and may reflect a general conservation of control mechanisms in vertebrate convergent extension.

Regulation of touch receptor differentiation by the Caenorhabditis elegans mec-3 and unc-86 genes

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 4107-4119 ◽  
Author(s):  
A. Duggan ◽  
C. Ma ◽  
M. Chalfie
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Fate ◽  
Binding Sites ◽  
Ectopic Expression ◽  
The Body ◽  
Specific Gene ◽  
Homeodomain Protein ◽  
Activation Domains ◽  
Cell Lineages

The nematode Caenorhabditis elegans possesses six morphologically similar neurons that are responsible for sensing gentle touch to the body. Previous genetic studies identified genes that are necessary for the production and differentiation of these touch cells. In particular, unc-86 encodes a POU-type homeodomain protein needed for the production of the touch cells, while mec-3 encodes a LIM-type homeodomain protein needed for the differentiation of the touch cells. Molecular studies showed that MEC-3 and UNC-86 bind cooperatively to sites in the mec-3 promoter and can synergistically activate transcription from it in vitro. Here we show that UNC-86::MEC-3 hetero-oligomer-binding sites are also found in the promoters of two presumed targets of mec-3, the mec-4 and mec-7 genes, that are necessary for the function of the touch cells. These sites, which are well-conserved in the related nematode C. briggsae, are required for promoter activity. When one of the binding sites is cloned into a heterologous promoter, expression is found in the touch cells and two to four other cells that express mec-3 and unc-86. These data support a model in which touch-cell differentiation is specified, in part, by the UNC-86::MEC-3 hetero-oligomer and not by MEC-3 alone. Ectopic expression of mec-3, driven by a heat-shock promoter, also supports this hypothesis: the acquisition of touch-cell characteristics by several additional cells under these conditions required unc-86. Since the touch-cell lineages express UNC-86 before MEC-3, MEC-3 appears to modify the activity of UNC-86, leading to touch-cell-specific gene expression. Because both UNC-86 and MEC-3 have activation domains, the formation of the hetero-oligomer may create a strong activator. In the modification of UNC-86 function by MEC-3 in the touch cells, these studies provide an example of how the sequential activation of transcription factors can determine cell fate within particular cell lineages.

Posterior apical ectodermal ridge removal in the chick wing bud triggers a series of events resulting in defective anterior pattern formation

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 501-515 ◽  
Author(s):  
W.L. Todt ◽  
J.F. Fallon
Keyword(s):  
Cell Death ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Direct Result ◽  
Posterior Border ◽  
Posterior Portion ◽  
Mesodermal Cell ◽  
Posterior Limb ◽  
Survival And Development ◽  
Wing Bud

The ability of the anterior apical ectodermal ridge to promote outgrowth in the chick wing bud when disconnected from posterior apical ridge was examined by rotating the posterior portion of the stage-19/20 to stage-21 wing bud around its anteroposterior axis. This permitted contact between the anterior and posterior mesoderm, without removing wing bud tissue. In a small but significant number of cases (10/54), anterior structures (digit 2) formed spatially isolated from posterior structures (digits 3 and 4). Thus, continuity with posterior ridge is not a prerequisite for anterior-ridge function in the wing bud. Nevertheless, posterior-ridge removal does result in anterior limb truncation. To investigate events leading to anterior truncation, we examined cell death patterns in the wing bud following posterior-ridge removal. We observed an abnormal area of necrosis along the posterior border of the wing bud at 6–12 h following posterior-ridge removal. This was followed by necrosis in the distal, anterior mesoderm at 48 h postoperatively and subsequent anterior truncation. Clearly, healthy posterior limb bud mesoderm is needed for anterior limb bud survival and development. We propose that anterior truncation is the direct result of anterior mesodermal cell death and that this may not be related to positional specification of anterior cells. In our view, cell death of anterior mesoderm, after posterior mesoderm removal, should not be used as evidence for a role in position specification by the polarizing zone during the limb bud stages of development. We suggest that the posterior mesoderm that maintains the anterior mesoderm need not be restricted to the mapped polarizing zone, but is more extensively distributed in the limb bud.

Regeneration of amputated limb-buds in early rat embryos

Development ◽  
1976 ◽  
Vol 35 (2) ◽  
pp. 345-354
Author(s):  
Elizabeth M. Deuchar
Keyword(s):  
Epidermal Cells ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Embryonic Cells ◽  
Roller Bottle ◽  
Limb Buds ◽  
Rat Embryos ◽  
Stage Of Development ◽  
Embryonic Limb ◽  
Vertebrate Embryos

Rat embryos, dissected from the uterus at 11½ days' gestation, have been used to study the regenerative powers of the embryonic limb. One forelimb-bud of each embryo was amputated, via an incision in the membranes. Embryos were subsequently grown in roller-bottle cultures for 44 h, then examined histologically. Twenty-nine out of 32 healthy embryos had formed limb-bud regenerates, 14 of which were of normal size and shape. Eight of them had a normal apical ectodermal ridge. It is concluded that at this stage of development there is sufficient versatility in the embryonic cells for a limb rudiment to be replaced by adjacent mesenchyme and epidermal cells. The implications of this finding are discussed in connexion with previous studies on the regeneration of appendages in vertebrate embryos.

Mesenchymal Stem Cells Differentiation: Mitochondria Matter in Osteogenesis or Adipogenesis Direction

2020 ◽  
Vol 15 (7) ◽  
pp. 602-606
Author(s):  
Kun Ji ◽  
Ling Ding ◽  
Xi Chen ◽  
Yun Dai ◽  
Fangfang Sun ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Therapeutic Potential ◽  
Mesodermal Cell ◽  
Cell Lineages ◽  
Current Review ◽  
Differentiation Factors ◽  
The Relationship ◽  
Msc Differentiation

Mesenchymal Stem Cells (MSCs) exhibit enormous therapeutic potential because of their indispensable regenerative, reparative, angiogenic, anti-apoptotic, and immunosuppressive properties. MSCs can best differentiate into mesodermal cell lineages, including osteoblasts, adipocytes, muscle cells, endothelial cells and chondrocytes. Specific differentiation of MSCs could be induced through limited conditions. In addition to the relevant differentiation factors, drastic changes also occur in the microenvironment to conduct it in an optimal manner for particular differentiation. Recent evidence suggests that the mitochondria participate in the regulating of direction and process of MSCs differentiation. Therefore, our current review focuses on how mitochondria participate in both osteogenesis and adipogenesis of MSC differentiation. Besides that, in our current review, we try to provide a further understanding of the relationship between the behavior of mitochondria and the direction of MSC differentiation, which could optimize current cellular culturing protocols for further facilitating tissue engineering by adjusting specific conditions of stem cells.

scholarly journals The EGL-13 SOX Domain Transcription Factor Affects the Uterine Cell Lineages in Caenorhabditis elegans

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1623-1628
Author(s):  
Hediye Nese Cinar ◽  
Keri L Richards ◽  
Kavita S Oommen ◽  
Anna P Newman
Keyword(s):  
Transcription Factor ◽  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Cell Fate ◽  
Cell Lineages

Abstract We isolated egl-13 mutants in which the cells of the Caenorhabditis elegans uterus initially appeared to develop normally but then underwent an extra round of cell division. The data suggest that egl-13 is required for maintenance of the cell fate.

scholarly journals Plasticity of proximal–distal cell fate in the mammalian limb bud

2008 ◽  
Vol 313 (1) ◽  
pp. 225-233 ◽  
Author(s):  
Laurie A. Wyngaarden ◽  
Sevan Hopyan
Keyword(s):  
Cell Fate ◽  
Limb Bud ◽  
Distal Cell

ming is expressed in neuroblast sublineages and regulates gene expression in the Drosophila central nervous system

Development ◽  
1992 ◽  
Vol 116 (4) ◽  
pp. 943-952 ◽  
Author(s):  
X. Cui ◽  
C.Q. Doe
Keyword(s):  
Gene Expression ◽  
Central Nervous System ◽  
Nervous System ◽  
Cell Fate ◽  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Cell Lineage ◽  
Cell Lineages ◽  
Finger Protein ◽  
Cell Diversity

Cell diversity in the Drosophila central nervous system (CNS) is primarily generated by the invariant lineage of neural precursors called neuroblasts. We used an enhancer trap screen to identify the ming gene, which is transiently expressed in a subset of neuroblasts at reproducible points in their cell lineage (i.e. in neuroblast ‘sublineages’), suggesting that neuroblast identity can be altered during its cell lineage. ming encodes a predicted zinc finger protein and loss of ming function results in precise alterations in CNS gene expression, defects in axonogenesis and embryonic lethality. We propose that ming controls cell fate within neuroblast cell lineages.

FGF-4 maintains polarizing activity of posterior limb bud cells in vivo and in vitro

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 199-206 ◽  
Author(s):  
A. Vogel ◽  
C. Tickle
Keyword(s):  
Posterior Margin ◽  
Anterior Margin ◽  
Marked Decrease ◽  
Mesenchymal Cells ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Posterior Limb ◽  
Vertebrate Limb

The polarizing region is a major signalling tissue involved in patterning the tissues of the vertebrate limb. The polarizing region is located at the posterior margin of the limb bud and can be recognized by its ability to induce additional digits when grafted to the anterior margin of a chick limb bud. The signal from the polarizing region operates at the tip of the bud in the progress zone, a zone of undifferentiated mesenchymal cells, maintained by interactions with the apical ectodermal ridge. A number of observations have pointed to a link between the apical ectodermal ridge and signalling by the polarizing region. To test this possibility, we removed the posterior apical ectodermal ridge of chick wing buds and assayed posterior mesenchyme for polarizing activity. When the apical ectodermal ridge is removed, there is a marked decrease in polarizing activity of posterior cells. The posterior apical ectodermal ridge is known to express FGF-4 and we show that the decrease in polarizing activity of posterior cells of wing buds that normally follows ridge removal can be prevented by implanting a FGF-4-soaked bead. Furthermore, we show that both ectoderm and FGF-4 maintain polarizing activity of limb bud cells in culture.

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