Properties of the primary organization field in the embryo of Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 27-46
Author(s):  
J. Cooke
Keyword(s):  
Early Stage ◽  
Organizer Region ◽  
Positional Information ◽  
Bilateral Symmetry ◽  
Angular Distance ◽  
Organ Differentiation ◽  
Primary Organization ◽  
Cell Commitment ◽  
Time Of Operation ◽  
Field Formation

The results are reported of a series of experiments, the exact geometry of which has been presented in a previous paper. Late blastulae and early stage-10 gastrulae are supplied with a second head organizer region at varying angular distances, in the marginal zone, from the presumptive site of their own organizer. The configuration of positional information existing in the mesodermal mantle of the late gastrula or earliest neurula, as a final result of such operations, was recorded by observing the pattern of axial organ differentiation obtained by tailbud stages (26–28). The operational differences between various current theories as to the nature of embryonic differentiation fields are briefly discussed, as a framework within which to consider the results of experiments such as those reported here. It is suggested that in the future, and using the present results as a basis, experiments may be possible that are more critical in distinguishing between the various theoretical suppositions involved. Evidence is presented that the final configuration of positional information, achieved as a result of the implantation of a second head organizer at or before the onset of host gastrulation, becomes stable some time before it is irreversibly expressed in terms of a pattern of cell commitment in the mesodermal/endodermal mantle. It is insensitive both to relative ages of host and graft at the time of operation, over the range employed and, probably, to the ambient temperature of development between operation and the time of cell differentiation, being dependent only on the angular distance originally existing between graft and presumptive host organizer sites. In the discussion, a model is given for the visualization of positional information in partially double fields, produced in a two-dimensional sheet of cells where the normal end-point of field formation is a bilateral symmetry of differentiation zones.

Properties of the primary organization field in the embryo of Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 13-26
Author(s):  
J. Cooke
Keyword(s):  
Marginal Zone ◽  
Organizer Region ◽  
Angular Distance ◽  
Cell Polarization ◽  
Subsequent Paper ◽  
Basic Operation ◽  
Primary Organization ◽  
Organizer Activity ◽  
Set Up ◽  
Cell Immigration

The work presented, in this and the subsequent papers of a series, was begun in order to re-examine the properties of the amphibian primary embryonic field, in the light of current theories concerning the nature of individuation fields in developing animal systems. A detailed description is given of the basic operation whose results are described in this and the subsequent paper. This involves the transplantation, into a late blastula or stage-10 gastrula host, of a supernumerary stage-10 organizer region. The consequences of such operations during the following 4–6 h, up to the late gastrula stage, are also described. Evidence is presented that, from a time some 2·5 h before the organizer site first becomes externally visible, its presumptive region is immune from interference by the proximity of another, implanted organizer, even one which is itself 2·5 h older. That is to say, the final site of development of host organizer activity is not altered by the presence of such an implant. Pairs of early organizers at comparable stages of activity appear to set up competing fields of cellular orientation and immigration, which show a fairly sharp boundary at their interface. This is most obvious for pairs of organizers fairly close together, since the cell polarization and stretching is most pronounced in the region near to the apex of the field, i.e. the initial site of cell immigration. Independent initial fields of immigration due to two organizers can reliably be distinguished in cases where they are as little as 30° of angular distance apart in the marginal zone of the host. These results are to be considered in relation to those of Paper II, for the same series of operations, where the final patterns of cell differentiation are studied, and to those of Paper III, where evidence is given for the development of autonomous polarity in the region of the organizer.

Properties of the primary organization field in the embryo of Xenopus laevis

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 283-300
Author(s):  
J. Cooke
Keyword(s):  
Organizer Region ◽  
Positional Information ◽  
Host Cells ◽  
Normal Embryo ◽  
Tail Bud ◽  
Essentially Normal ◽  
Head Formation ◽  
Source Data ◽  
Primary Organization ◽  
Host Embryo

Patterns of individuation occurring in the primary embryonic axis of Xenopus following excision of the organizer region of the early gastrula are described. In some 70% of cases the information for induction of the complete head is qualitatively restored by the time of cell determination, giving rise to an essentially normal embryo. In some 40% of cases a second posterior axis of bilaterality is formed, causing development of a secondary anus, tail-fin and spinal cord, and often somites. The probabilities of twinning in the tailfield and of failure to complete apical regulation (= head formation) are largely independent. After such excision of the head organizer region, a delay of some 3 h in the schedule of visible differentiation in the neurula/tail-bud embryo is commonly incurred, whether or not apical regulation is successful. When the apex is excised from a host embryo which has already contained for some hours a second apex (= head organizer) as described in an earlier paper, that grafted apex then captures a considerably increased territory in the host material, as seen from the size of the individuation field finally caused by it. Such a shift across host cells, of the boundary between fields of positional information due to two organizers, is not seen under any conditions where these are left intact, or where host excision is carried out soon after implanting the donor organizer. In discussing the results and reconciling them with earlier observations, it is shown that they strongly suggest the presence of local polar (i.e. vectorial) properties in the presumptive mesoderm, due to signals from restricted regions which have achieved a special apical state. Repolarization of cells by a new organizer is not very rapid, and may spread decrementally from the source. Data on further delays in development, caused by the presence of the second organizer during regulation in the host apex, suggest that one organizer may act directly on cells elsewhere to delay or prevent the restoration of the apical state there.

scholarly journals EBF1 is expressed in pericytes and contributes to pericyte cell commitment

2021 ◽  
Author(s):  
Francesca Pagani ◽  
Elisa Tratta ◽  
Patrizia Dell’Era ◽  
Manuela Cominelli ◽  
Pietro Luigi Poliani
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Mesenchymal Stem Cells ◽  
B Cell ◽  
Cell Fate ◽  
Early Stage ◽  
Cell Lineage ◽  
Cell Maturation ◽  
Cell Commitment

AbstractEarly B-cell factor-1 (EBF1) is a transcription factor with an important role in cell lineage specification and commitment during the early stage of cell maturation. Originally described during B-cell maturation, EBF1 was subsequently identified as a crucial molecule for proper cell fate commitment of mesenchymal stem cells into adipocytes, osteoblasts and muscle cells. In vessels, EBF1 expression and function have never been documented. Our data indicate that EBF1 is highly expressed in peri-endothelial cells in both tumor vessels and in physiological conditions. Immunohistochemistry, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and fluorescence-activated cell sorting (FACS) analysis suggest that EBF1-expressing peri-endothelial cells represent bona fide pericytes and selectively express well-recognized markers employed in the identification of the pericyte phenotype (SMA, PDGFRβ, CD146, NG2). This observation was also confirmed in vitro in human placenta-derived pericytes and in human brain vascular pericytes (HBVP). Of note, in accord with the key role of EBF1 in the cell lineage commitment of mesenchymal stem cells, EBF1-silenced HBVP cells showed a significant reduction in PDGFRβ and CD146, but not CD90, a marker mostly associated with a prominent mesenchymal phenotype. Moreover, the expression levels of VEGF, angiopoietin-1, NG2 and TGF-β, cytokines produced by pericytes during angiogenesis and linked to their differentiation and activation, were also significantly reduced. Overall, the data suggest a functional role of EBF1 in the cell fate commitment toward the pericyte phenotype.

Rôle du mésoderme somitique dans le développement du plumage dorsal chez l'embryon de Poulet

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 343-366
Author(s):  
Par Annick Mauger
Keyword(s):  
Early Stage ◽  
Cervical Region ◽  
Lumbar Region ◽  
Chick Embryos ◽  
A Chain ◽  
Normal Differentiation ◽  
Time Of Operation ◽  
Somitic Mesoderm ◽  
Axial Organs

The role of somitic mesoderm in the development of dorsal plumage in chick embryos. II. Regionalisation. Transplantation and inversion experiments were performed on the somitic mesoderm of 2- to 2·5-day chick embryos in order to study the role of regional and axial determinations in the development of the dorsal plumage. The transposition of a piece of somitic mesoderm from the posterior cervical region (where the spinal pteryla is narrow) to the thoraco-lumbar region (where it is wide) leads to a local and unilateral narrowing of the spinal pteryla at the operation site. Conversely, the transposition of somitic mesoderm from the thoraco-lumbar region to the posterior cervical region results in a local and unilateral widening of the spinal pteryla. Consequently at the time of operation the segmented or not yet segmented somitic mesoderm is already determined to give rise to a definite transverse level of the spinal pteryla. The inversion of the cephalo-caudal polarity of a piece of somitic mesoderm without the ectodermal covering, or of a portion of the axial organs deprived of the overlying ectoderm has no effect on the orientation of feather filaments and feather rows. In contrast, the inversion of the cephalo-caudal polarity of a portion of the axial organs together with the overlying ectoderm results in the development of feathers growing in a cephalad direction and feather chevrons opening towards the head of the embryo. The inversion of the dorso-ventral polarity of a piece of somitic mesoderm does not prevent the normal differentiation of feathers in the operated region. The inversion of the medio-lateral polarity of a piece of unsegmented somitic mesoderm has little effect on the development of the spinal pteryla. On the contrary, the medio-lateral inversion of a chain of somites precludes the formation of the feathers at the level of operation. The somitic mesoderm, even when segmented, is endowed with extensive regulative capacity of its axes, except for the medio-lateral polarity, which is fixed irreversibly at the time of segmentation. The regional determination of the feather-forming somitic mesoderm is acquired at an early stage, at any rate before segmentation. However, at a given transverse level of the cephalo-caudal axis, the somitic cells remain totipotent as concerns their histo-genetic destiny (dermatome, myotome, or sclerotome) until after the onset of segmentation.

Dynamics of the control of body pattern in the development of Xenopus laevis

Development ◽  
1985 ◽  
Vol 88 (1) ◽  
pp. 85-112
Author(s):  
Jonathan Cooke ◽  
John A. Webber
Keyword(s):  
Body Position ◽  
Posterior Part ◽  
Frontal Plane ◽  
Positional Information ◽  
Bilateral Symmetry ◽  
The Body ◽  
Fate Map ◽  
Amphibian Embryo ◽  
Larval Stages ◽  
Body Pattern

Xenopus embryos have been selected in which the second cleavage is occuring in a frontal plane, i.e one tending to lie at right angles to the prospective plane of bilateral symmetry for the body pattern. Some of these have been used to deduce a map of the disposition of materials for the normal mesodermal pattern (the normal ‘fate map’) by injecting blastomeres to found fluorescently marked clones from 4- to 32-cell stages. Other such 4-cell embryos have been separated into two isolates across this second cleavage; in fate-map terms, prospective dorsoanterior and posterior isolates. These have been allowed to develop to control axial larval stages, with examination of the time schedule of their gastrulation movements in relation to cofertilized whole controls. The patterns of mesoderm produced have been examined and interpreted in the light of quantitative knowledge about the normal pattern, and our current understanding of the map. A meaningful fate map exists for the egg material even at this early, essentially acellular stage, and it differs appreciably from what might have been expected in view of that traditionally shown for early gastrula stages. The patterns developed in the isolates show that at least in many eggs, widespread information that positively specifies material as to its body position is available from at most 1 h after the events that give rise to bilateral symmetry upon fertilization. This information usually leads to a mosaic development of the appropriate mesodermal part-pattern in dorsoanterior isolates, and frequently allows development that approximates to this in the reciprocal posterior part. Regulation, i.e. the replacement of removed information to specify a development more complete than the normal contribution in isolates, is not observed. The results suggest a revision of former claims for regulative ability in at least this amphibian embryo. They also imply that systems for ascribing position value (positional information) to early embryonic tissue can be diverse in dynamics, even among embryos whose body plans are obviously homologous as are those of vertebrates.

Cortical rotation of the Xenopus egg: consequences for the anteroposterior pattern of embryonic dorsal development

Development ◽  
1989 ◽  
Vol 107 (Supplement) ◽  
pp. 37-51 ◽  
Author(s):  
J. Gerhart ◽  
M. Danilchik ◽  
T. Doniach ◽  
S. Roberts ◽  
B. Rowning ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Organizer Region ◽  
Bilateral Symmetry ◽  
Cylindrical Symmetry ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Proximate Cause ◽  
Spemann Organizer ◽  
Anterior Dorsal ◽  
Xenopus Egg

We first review cortical–cytoplasmic rotation, a microtubule-mediated process by which the Xenopus egg, like other amphibian eggs, transforms its polarized cylindrical symmetry into bilateral symmetry within the first cell cycle after fertilization. This transformation, the earliest of many steps leading to dorsal development, involves the displacement of the egg's cortex relative to its cytoplasmic core by 30° in an animal–vegetal direction. As rotation is progressively reduced by microtubuledepolymerizing agents, embryos develop with body axes progressively deleted for dorsal structures at the anterior end. With no rotation, ventralized embryos are formed. In an effort to comprehend this progressive effect on embryonic organization, we go on to review subsequent developmental processes depending on rotation, and we propose, with evidence, that reduced rotation leads to a reduced number of vegetal dorsalizing cells, which induce during the blastula stage a Spemann organizer region of smaller than normal size. The reduced organizer then promotes a reduced amount of cell rearrangement (morphogenesis) at gastrulation. Reduced morphogenesis seems the proximate cause of the incompleteness of axial pattern, as shown further by the fact that embryos that are normal until the gastrula stage, if exposed to inhibitors of morphogenesis, develop body axes that are progressively less complete in their anterior dorsal organization the earlier their gastrulation had been blocked. We discuss why axial pattern might depend systematically on morphogenesis.

scholarly journals Verrucous Carcinoma of the Foot with Bone Invasion: A Case Report

2013 ◽  
Vol 2013 ◽  
pp. 1-3 ◽  
Author(s):  
C. Pempinello ◽  
A. Bova ◽  
R. Pempinello ◽  
R. Luise ◽  
G. Iannaci
Keyword(s):  
Early Stage ◽  
Verrucous Carcinoma ◽  
Focal Lesion ◽  
Multiple Biopsies ◽  
Pathological Evaluation ◽  
Delays In Diagnosis ◽  
Leg Amputation ◽  
Time Of Operation ◽  
Topical Medications ◽  
Chronic Course

Verrucous carcinoma of the foot often affects deep structures such as tendons, muscles, or bones. A 74-year-old man presented with a foot lesion that had been diagnosed as a skin infection 7 years earlier. He was treated with multiple excisions and superficial biopsies associated with antibiotic therapy without success. In our department he underwent an aggressive and accurate debridement with marginal excision harvesting multiple biopsies. Pathological evaluation of tissue at the time of operation confirmed the diagnosis of verrucous carcinoma of the foot. Therefore, the patient underwent an amputation below knee, and there were no postoperative complications; the patient was able to walk with the aid of a prosthesis with no signs of recurrence. The lesion follows a chronic course evolving from a discrete focal lesion to a large fungating deeply penetrating mass often compromised by local infection. The slow growth and confusing early-stage appearances can lead to delays in diagnosis of 8 to 15 years causing the extracutaneous involvement that requires a leg amputation. Many patients are initially treated with many topical medications without success, and most tumors have been treated as recalcitrant warts or corns for some time, whereas the basic approach is surgical.

scholarly journals Cytogenetic characterization of Hypostomus soniae Hollanda-Carvalho & Weber, 2004 from the Teles Pires River, southern Amazon basin: evidence of an early stage of an XX/XY sex chromosome system

2019 ◽  
Vol 13 (4) ◽  
pp. 411-422 ◽  
Author(s):  
Luciene Castuera de Oliveira ◽  
Marcos Otávio Ribeiro ◽  
Gerlane de Medeiros Costa ◽  
Cláudio Henrique Zawadzki ◽  
Ana Camila Prizon-Nakajima ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Sex Chromosome ◽  
Early Stage ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Structural Difference ◽  
Chromosomal Polymorphism ◽  
Nucleolus Organizer ◽  
Rdna Sites ◽  
Sex Chromosome System

In the present study, we analyzed individuals of Hypostomus soniae (Loricariidae) collected from the Teles Pires River, southern Amazon basin, Brazil. Hypostomus soniae has a diploid chromosome number of 2n = 64 and a karyotype composed of 12 metacentric (m), 22 submetacentric (sm), 14 subtelocentric (st), and 16 acrocentric (a) chromosomes, with a structural difference between the chromosomes of the two sexes: the presence of a block of heterochromatin in sm pair No. 26, which appears to represent a putative initial stage of the differentiation of an XX/XY sex chromosome system. This chromosome, which had a heterochromatin block, and was designated proto-Y (pY), varied in the length of the long arm (q) in comparison with its homolog, resulting from the addition of constitutive heterochromatin. It is further distinguished by the presence of major ribosomal cistrons in a subterminal position of the long arm (q). The Nucleolus Organizer Region (NOR) had different phenotypes among the H. soniae individuals in terms of the number of Ag-NORs and 18S rDNA sites. The origin, distribution and maintenance of the chromosomal polymorphism found in H. soniae reinforced the hypothesis of the existence of a proto-Y chromosome, demonstrating the rise of an XX/XY sex chromosome system.

Developmental aspects of tristyly in Lythrum salicaria

1998 ◽  
Vol 76 (7) ◽  
pp. 1214-1226 ◽  
Author(s):  
Tarun K Mal
Keyword(s):  
Growth Rate ◽  
Cell Size ◽  
Early Stage ◽  
Lythrum Salicaria ◽  
Growth Patterns ◽  
Epidermal Cells ◽  
Growth Stages ◽  
Relative Growth ◽  
Organ Differentiation ◽  
Intermediate Cells

The developmental basis of floral polymorphism was investigated in the tristylous invasive species, Lythrum salicaria L. (Lythraceae). In tristylous species, the stigmas are positioned above (in the long morph), below (in the short morph), or between (in the mid morph) the outer and inner staminal whorls. Flower samples were collected at three different growth stages (early, pre-anthesis, and post-anthesis) from three genotypes from each of the three morphs to observe morph-specific differences in growth patterns of filaments and styles and their constituent epidermal cells. From each flower, I measured the length of styles and two types of stamens and their epidermal cells at the basal, intermediate, and apical regions of each organ. Differentiation of organ levels begins at a very early stage. Growth rate of the long pistil is higher than in the mid pistil followed by the short pistil. However, the growth rate of epidermal cells is higher in the short style followed by the mid and long styles. The number of cells does not increase during style development in the short morph but does increase in the long and mid morphs. Although the relative growth of the outer stamens is greater than in the inner stamens in all three morphs, the relative cell size is greater in the inner stamens than in the outer stamens. Cell size differs between outer and inner stamens in the long and mid morphs but not in the short morph. The intermediate cells are larger compared with the basal and apical cells of the stamens and styles. The number of epidermal cells increases in the outer stamens during development, whereas it remains constant in the inner stamens of the mid morph and increases only slightly in the inner stamens of long morph.Key words: floral development, growth and division of epidermal cells, heterostyly, purple loosestrife, style and stamen growth, style-stamen polymorphism.

Early Contingent Negative Variation (CNV) Shows a Small Symmetrical Negativity in a Somatosensory Paradigm

2002 ◽  
Vol 33 (2) ◽  
pp. 77-81
Author(s):  
Yasuharu Sato ◽  
Hirooki Yabe ◽  
Tomiharu Hiruma ◽  
Takeyuki Sutoh ◽  
Naoko Shinozaki ◽  
...  
Keyword(s):  
Contingent Negative Variation ◽  
Early Stage ◽  
Light Flash ◽  
Red Light ◽  
Event Related Potentials ◽  
Bilateral Symmetry ◽  
P300 Latency ◽  
Warning Stimulus ◽  
Related Potentials ◽  
Conventional Paradigm

The influence of sensory modulation on the early stage of information processing was investigated with a somatosensory contingent negative variation (CNV) paradigm. Whether or not even a somatosensory input as well as auditory or visual stimulus to one hemisphere elicits the symmetrical “early CNV” was also examined. Eleven normal individuals (3 males, 8 females) performed a conventional CNV paradigm with a click sound as the warning stimulus (WS) and a red light flash as the imperative stimulus (IS). Nine individuals (5 males, 4 females) did the somatosensory CNV paradigm with paired electrical stimuli as WS and IS. The subjects were instructed to press a button in response to IS as fast as possible. The early CNV amplitude was smaller and P300 latency was longer in somatosensory paradigm than conventional paradigm. In addition, the latency of P100 in a somatosensory paradigm was longer than that of N100 in a conventional paradigm. These findings suggest that the initiation of early detection, reflected by P100, the initiation of cognition, reflected by P300, and orienting response, reflected by early CNV, are delayed in a somatosensory CNV paradigm. Furthermore, all event-related potentials (ERPs) evoked by somatosensory stimuli showed a bilateral symmetry.

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