scholarly journals Intrinsic and extrinsic modifiers of the regulative capacity of the developing liver

2012 ◽  
Vol 128 (11-12) ◽  
pp. 525-535 ◽  
Author(s):  
Donghun Shin ◽  
Gilbert Weidinger ◽  
Randall T. Moon ◽  
Didier Y.R. Stainier
Keyword(s):  
Regulative Capacity

Regulative capacity of the archenteron during gastrulation in the sea urchin

Development ◽  
1996 ◽  
Vol 122 (2) ◽  
pp. 607-616 ◽  
Author(s):  
D.R. McClay ◽  
C.Y. Logan
Keyword(s):  
Sea Urchin ◽  
Short Range ◽  
Endodermal Cells ◽  
Regulative Capacity

Gastrulation in the sea urchin involves an extensive rearrangement of cells of the archenteron giving rise to secondary mesenchyme at the archenteron tip followed by the foregut, midgut and hindgut. To examine the regulative capacity of this structure, pieces of the archenteron were removed or transplanted at different stages of gastrulation. After removal of any or all parts of the archenteron, the remaining veg 1 and /or veg 2 tissue regulated to replace the missing parts. Endoderm transplanted to ectopic positions also regulated to that new position in the archenteron. This ability to replace or regulate endoderm did not decline until after full elongation of the archenteron was completed. When replacement occurred, the new gut was smaller relative to the remaining embryo but the recognizable morphology of the archenteron was re-established. Long after the archenteron reveals territorial specification through expression of specific markers, the endodermal cells remain capable of being respecified to other gut regions. Thus, for much of gastrulation, the gut is conditionally specified. We propose that this regulative ability requires extensive and continuous short-range communication between cells of the archenteron in order to reorganize the tissues and position the boundaries of this structure even after experimental alterations.

Hedgehog is required for activation of engrailed during regeneration of fragmented Drosophila imaginal discs

Development ◽  
1999 ◽  
Vol 126 (8) ◽  
pp. 1591-1599 ◽  
Author(s):  
M.C. Gibson ◽  
G. Schubiger
Keyword(s):  
Normal Growth ◽  
Imaginal Discs ◽  
Ideal Model ◽  
Posterior Compartment ◽  
Anterior Compartment ◽  
In Vivo Culture ◽  
Pattern Regulation ◽  
Regulative Capacity ◽  
Anterior Posterior

Surgically fragmented Drosophila appendage primordia (imaginal discs) engage in wound healing and pattern regulation during short periods of in vivo culture. Prothoracic leg disc fragments possess exceptional regulative capacity, highlighted by the ability of anterior cells to convert to posterior identity and establish a novel posterior compartment. This anterior/posterior conversion violates developmental lineage restrictions essential for normal growth and patterning of the disc, and thus provides an ideal model for understanding how cells change fate during epimorphic pattern regulation. Here we present evidence that the secreted signal encoded by hedgehog directs anterior/posterior conversion by activating the posterior-specific transcription factor engrailed in regulating anterior cells. In the absence of hedgehog activity, prothoracic leg disc fragments fail to undergo anterior/posterior conversion, but can still regenerate missing anterior pattern elements. We suggest that hedgehog-independent regeneration within the anterior compartment (termed integration) is mediated by the positional cues encoded by wingless and decapentaplegic. Taken together, our results provide a novel mechanistic interpretation of imaginal disc pattern regulation and permit speculation that similar mechanisms could govern appendage regeneration in other organisms.

scholarly journals Multiplying embryos: experimental monozygotic polyembryony in mammals and its uses

2019 ◽  
Vol 63 (3-4-5) ◽  
pp. 143-155
Author(s):  
Ellen Casser ◽  
Steffen Israel ◽  
Michele Boiani
Keyword(s):  
Embryo Quality ◽  
Interindividual Variation ◽  
Phenotypic Traits ◽  
Cleavage Stage ◽  
Cell Stage ◽  
Species Specific ◽  
Real Gain ◽  
Original Motivation ◽  
Mz Twins ◽  
Regulative Capacity

Monozygotic (MZ) polyembryony is a strategy to increase the output of a single zygote, thereby producing more offspring from a limited number of oocytes. However, MZ twins and multiples (multiplets) of mammals occur rarely in nature, while their generation has been more successful experimentally. In this work, we review some of the methodological, biological and field aspects of experimental MZ polyembryony in mammals. First attempts of mechanical bisection of 2-cell stage rodent embryos provided a proof-of-principle for the survival and independent development of both blastomeres. Subsequently, experiments in other species, particularly sheep and bovine, allowed 2 methods of embryo multiplication to become routine: the separation or biopsy of blastomeres from cleavage-stage embryos and the bisection of morulae and blastocysts. We discuss how the preferable stage of bisection and the success rate can be species-specific. The scope that profited most from experimental MZ polyembryony is the production of additional copies of elite livestock individuals, the reduction of interindividual variation in test groups and the possibility of investigating discordant phenotypic traits in the same genomic background, for instance, comparing an affected twin with its healthy co-twin. By contrast, the original motivation for experimental polyembryony – efficiently generating more offspring out of the same zygote – has not been fulfilled yet. Although embryo splitting leads to an increase in quantity, there is a loss of embryo quality, thus, there is no real gain from artificially generated embryos (yet) in the field of medically assisted reproduction. In conclusion, mammalian zygotes have the regulative capacity to be polyembryonic, but this is not obligate.

Regulative capacity of glutamine

2003 ◽  
Vol 6 (3) ◽  
pp. 277-282 ◽  
Author(s):  
Rudolf Oehler ◽  
Erich Roth
Keyword(s):  
Regulative Capacity

scholarly journals Human Naïve Epiblast Cells Possess Unrestricted Lineage Potential

2020 ◽  
Author(s):  
Ge Guo ◽  
Giuliano Giuseppe Stirparo ◽  
Stanley Strawbridge ◽  
Daniel Spindlow ◽  
Jian Yang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Human Embryo ◽  
Embryonic Stem ◽  
Trophoblast Stem Cells ◽  
Assisted Reproduction Technology ◽  
Trophoblast Stem ◽  
Genetic Perturbations ◽  
Cell Propagation ◽  
Post Implantation ◽  
Regulative Capacity

SUMMARYClassical mouse embryology has established a paradigm of early development driven by sequential lineage bifurcations. Accordingly, mouse embryonic stem cells derived from early epiblast have lost the potency to produce extraembryonic trophectoderm. We show in contrast that human naïve epiblast cells readily make trophectoderm. Inhibition of ERK signalling, instrumental in naïve stem cell propagation, unexpectedly potentiates trophectoderm formation, an effect enhanced by Nodal inhibition. Transcriptome analyses authenticate conversion into trophectoderm with subsequent production of syncitiotrophoblast, cytotrophoblast and trophoblast stem cells. Genetic perturbations indicate that NANOG suppresses and TFAP2C enables trophectoderm induction. Consistent with post-implantation progression, trophectoderm potential is extinguished in conventional human pluripotent stem cells, which instead make amnion. Finally, human embryo epiblasts from late blastocysts efficiently generate trophectoderm and differentiated trophoblast. Thus, pluripotent cells in the human embryo retain extraembryonic lineage plasticity and regenerative potential until implantation. Harnessing this unanticipated regulative capacity may be beneficial for assisted reproduction technology.

scholarly journals Regulative capacity for eye formation by first quartet micromeres of the polychaete Capitella teleta

2016 ◽  
Vol 410 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Emi Yamaguchi ◽  
Leah C. Dannenberg ◽  
Aldine R. Amiel ◽  
Elaine C. Seaver
Keyword(s):  
Capitella Teleta ◽  
Regulative Capacity ◽  
Eye Formation

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

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 313-341
Author(s):  
Par Annick Mauger
Keyword(s):  
Japanese Quail ◽  
Neural Tube ◽  
The State ◽  
Characteristic Pattern ◽  
Chick Embryos ◽  
Dorsal Skin ◽  
Dermal Cells ◽  
Somitic Mesoderm ◽  
Regulative Capacity

The role of somitic mesoderm in the development of dorsal plumage in chick embryos. I. Origin, regulation capacity and determination The role of somitic mesoderm in the development of the dorsal plumage has been studied in chick embryos. The operations were performed at 2–2·5 days of incubation. The replacement of a portion of somitic mesoderm by somitic mesoderm labelled with [3H]thymidine or obtained from Japanese quail embryos (whose nuclei bear distinctive specific markers) showed that cells originating from the dermatomes build up the dermis of the dorsal skin only. They do not migrate farther than approximately midway down the flank. Beyond this limit, dermal cells originate from the somatopleural mesoderm. The unsegmented somitic mesoderm is capable of extensive regulation, which leads to the development of a dorsal plumage, normal in the number and arrangement of its feathers according to the characteristic pattern of the spinal pteryla. Uni- or bilateral excision of segmented somitic mesoderm resulted in dorsal plumage deficiencies, the extent and frequency of which was related to the state of differentiation of the excised mesoderm. Thus, the excision of somites generally led to an incomplete spinal pteryla (absence of feather rows, apteria). However, the somitic mesoderm is still capable of regulation even though it has already undergone its differentiation into dermatome, myotome and sclerotome. These results show that somitic mesoderm retains its regulative capacity, even though it has already acquired its feather-forming determination. The replacement of unsegmented somitic mesoderm by various implants (agar, tantalum, gut, neural tube, somatopleural mesoderm), intended to block the regulation processes, abolished the differentiation of the spinal feathers on the operated side. In some cases, the implantation of somatopleural mesoderm resulted in the formation of a supernumerary tract. No tissue other than somitic mesoderm – not even the somatopleural mesoderm, which is normally in part feather-forming – is able to give rise to region-specific spinal pteryla dermis. The excision and replacement of somitic mesoderm prevented the differentiation of dense dermis, whereas these operations had no effect on the early histogenesis of the epidermis, with the formation of arches and anchor filaments.

Experimental studies on the organization of the preimplantation mouse embryo

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 255-261
Author(s):  
M. Susan Stern
Keyword(s):  
Normal Development ◽  
Developmental Stages ◽  
Experimental Studies ◽  
Subsequent Development ◽  
Cell Numbers ◽  
Preimplantation Mouse Embryo ◽  
Preimplantation Mouse ◽  
Partial Dissociation ◽  
Complete Dissociation ◽  
Regulative Capacity

The reaggregation and subsequent development of a range of disaggregated embryos has been examined: 1. Following complete dissociation embryos from 8-cell to late blastocyst reaggregated and developed to form morphologically normal blastocysts, even when blastomeres of two different developmental stages were present in the reaggregate. 2. Dissociated mid-blastocysts could also reaggregate to form blastocysts but more commonly they produced vesiculated masses, as did disaggregates of late blastocysts. 3. Successful fusion of pairs of mid or late blastocysts, with full cell numbers, was achieved following partial dissociation. These results are discussed in relation to blastocyst formation. It is suggested that even if the embryo derives polarity from the oocyte it is not functionally essential to normal development in view of the remarkable regulative capacity of the egg.

The regulative capacity of the node region

1960 ◽  
Vol 143 (2) ◽  
pp. 221-238 ◽  
Author(s):  
Ross L. Shoger
Keyword(s):  
Regulative Capacity
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