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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science
    Wound repair and regeneration 6 (1998), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study addresses the cellular mechanism of the nerve requirement for regeneration of the urodele forelimb. Others have suggested that only the Schwann cell lineage of the blastema requires nerves for regeneration and that upon limb denervation, Schwann cells arrest in the cell cycle and produce a factor that inhibits the cycling of the remaining blastema cells. Our objective was to test this Schwann cell inhibitor model. First, pieces of peripheral nerve were implanted into partially denervated (one third of the nerve supply cut) axolotl forelimbs in an attempt to provide sufficient additional Schwann cells to increase the threshold nerve requirement above that provided by the remaining nerves. These limbs showed delayed regeneration in 68% of the cases and mild deformities, as seen by Victoria Blue staining, in 10% of the cases, as compared with control, partially denervated contralateral limbs that received grafts of muscle or frozen/thawed nerve. Second, when pieces of peripheral nerve were implanted into fully innervated newt limbs, blastema formation was limited, and regeneration was delayed in 80% of experimental cases when compared with control, contralateral newt limbs with muscle or frozen/thawed nerve implants. The results support the inhibition model and further link the need for nerves in regeneration to a possible specific requirement by Schwann cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science
    Wound repair and regeneration 4 (1996), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: After amputation of a salamander limb, the extracellular matrix undergoes remodeling. The extracellular matrix that maintains the differentiated state of limb tissues is broken down and replaced by an extracellular matrix essential for dedifferentiation and blastema formation. We used monoclonal antibodies in immunohistochemistry methods and riboprobes in in situ hybridization to evaluate the upregulation of tenascin, type XII collagen, fibronectin, and the MT5 antigen. The Stump 1 antigen, an extracellular matrix protein that is abundant in the normal limb, is downregulated during regeneration and reappears late in regeneration as differentiation occurs. In the embryo, the Stump 1 antigen is also absent from the early limb bud and first appears during differentiation stages. Tenascin and fibronectin are also upregulated in the limb bud of the embryo, and these two extracellular matrix proteins appear to function during limb regeneration in adults and limb development in embryos. However, type XII collagen and the MT5 antigen are not found in the limb bud, indicating that type XII collagen and the MT5 antigen have roles in the regenerating limb but not in the embryo limb bud.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 268 (1977), S. 49-50 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Whole skin was grafted over the amputation surfaces of 57 adult newt (Notophthalmus viridescens) limb stumps immediately after amputation of the limbs through the proximal portion of the radius and ulna as previously described5. Newts remained anaesthetised on moist gauze for 2 h and were ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 202 (1995), S. 153-164 
    ISSN: 1058-8388
    Keywords: Regeneration ; Fibronectin ; Blastema ; Newt ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Using monoclonal antibodies (mAbs) reactive to newt limb regenerates, we hope to gain insight into the identity and function of regeneration significant molecules. mAb MT4 (matrix 4) identifies an extracellular matrix (ECM) protein that is strongly up-regulated first in the distal stump and then in the blastema during regeneration. Within the first 24 hr after amputation the MT4 antigen is localized to an acellular space beneath the wound epithelium, and first appears in the basal cells of the wound epithelium between days 5 and 7. At mid-bud blastema stages, the MT4 antigen is homogeneously distributed as thin fibers in the blastema ECM, and is later largely restricted to the distal tip of the blastema and the areas of cartilage condensation. After extraction and immunoblotting, the MT4 antigen was observed as three reduced species of Mr 225, 250, and 260. Taken together, the immunoblot and immunocytochemistry results suggested that mAb MT4 recognized newt fibronectin (FN). Sequence from a cDNA (NvFN.10) obtained by screening a newt blastema cDNA expression library with mAb MT4 conclusively identified the MT4 antigen as FN. To further investigate the expression of FN in regeneration, cDNA NvFN.10 was used to construct a riboprobe and in situ hybridization was done. In the unamputated limb only a few scattered cells expressed the FN gene. Within the first 3 days after amputation strong hybridization signal was observed in the basal cells of the wound epithelium. Most of the stump cells that dedifferentiated and accumulated beneath the wound epithelium at 7 days expressed the FN gene, while the basal cells of the wound epithelium maintained their expression. At mid- and late-bud blastema stages the vast majority of the blastema cells were strongly expressing the FN gene, but the wound epithelial cells now showed only weak FN transcription. Thus initially FN comes from the plasma. Then FN is synthesized by both the wound epithelium and mesenchyme. Finally, at blastema stages FN is produced primarily by the mesenchyme. The expression pattern of FN throughout regeneration suggests that this glycoprotein has roles in wound epithelial and mesenchymal cell migration and mesenchymal cell proliferation and differentiation. © 1995 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 265-271 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: mAb WE3 recognizes an antigen that is developmentally regulated in the wound epithelium of regenerating newt limbs. The antigen is precociously expressed when pieces of WE3-negative wound epithelium axe grafted subcutaneously (Tassava et al.: Recent Trends in Regeneration Research. New York: Plenum Publishing Co., pp. 37-49, 1989). In the present study, we investigated whether the WE3 antigen is expressed in epidermis of subcutaneous grafts of skin. Small pieces of limb skin were grafted into small tunnels in the lower jaw, limb, and tail, oriented either the same as (epidermis facing out) or opposite to (epidermis facing in) the orientation of the host skin. In most cases, the epithelium migrated from the graft along the wounded surface of the tunnel, closed onto itself, and formed a multilayered “emigrant” epithelium. Infrequently, the migrating epithelium combined with the wound epithelium of the insertion wound. In no case did the epithelium migrate over the cut edge of the grafted dermis. Reactivity to mAb WE3 was first seen at 4 days after grafting, when the migrating epithelium had almost closed over onto itself. By 6 days and thereafter, the entire emigrant epithelium was reactive to mAb WE3. While initially restricted to the emigrant epithelium, at 10 days after grafting and thereafter, reactivity was also seen in the epidermis that remained in contact with the dermis. Expression of the WE3 antigen was not influenced by the orientation of the graft nor by the graft site. The results show that, compared to amputated limbs, the epithelium originating from these grafts precociously expresses the WE3 antigen. Also, epidermis of grafted skin is capable of expressing the WE3 antigen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hypophysectomized adult newts exhibited 98% survival and limb regeneration at 23 days post-hypophysectomy when injected intraperitoneally every other day with prolactin (0.015 U/newt) and kept continuously in aquaria with 1 × 10-7 concentration of thyroxine. Thyroxine alone was no more effective than saline injections.Prolactin (1.2 U/newt every other day) alone increased survival and limb regeneration, but less effectively than did the prolactin-thyroxine combination.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normally, urodele limb regeneration is nerve-dependent. Reduction in nerve-dependency has been reported for regenerating, transplanted newt limbs (Singer and Mutterperl, '63). Aneurogenic limbs can regenerate without nerves (Yntema, '59). Induction of supernumerary limbs may be obtained from aneurogenic limbs of larval Ambystoma after transplantation orthotopically to innervated larvae and with normal nerve ingrowth to the limb transplant prevented by repeated section of brachial nerves. Of the 13 (of 43) grafts with supernumeraries, nerve counts showed 11 with 0-5; 1 with 5-10; and 1 with 20+ fibers. Orthotopically grafted aneurogenic limbs allowed to become innervated showed 14 supernumeraries in 49 grafts. This supernumerary limb induction is thus not nerve-dependent.Normally, innervated larval Ambystoma limbs grafted orthotopically and heteroplastically regenerated in 17 of 37 cases after repeated section of brachial nerves. Of the 17 regenerates nerve counts showed 4 with 0-5; 5 with 5-10; 7 with 10-19; and 1 with 20+ fibers. Larval limbs heteroplastically transplanted may require very few or no nerves for regeneration.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 213 (1992), S. 159-169 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Monoclonal antibody (mAb) WE3 recognizes an antigen that is developmentally expressed in the wound epithelium during adult newt limb regeneration. Experiments were designed to determine whether retinoic acid (RA), dissolved in dimethyl sulfoxide (DMSO) and administered by intraperitoneal injection, would enhance the temporal appearance of the WE3 antigen. RA given on days 1 or 4 after amputation, when the WE3 antigen is not yet detectable, resulted in moderate reactivity to mAb 2 days after injection and strong reactivity throughout the wound epithelium 4 days after injection. DMSO alone had no enhancing effect. RA also caused limb skin epidermis to exhibit reactivity to mAb WE3, initially near the amputation level, but then also more proximally. By 4 and 6 days after RA injection, epidermis of the flank, eye lid, and unamputated hind limbs also became strongly reactive to mAb WE3. Outer layers of skin epidermis were shed, resulting in an epidermis only one or two cells thick. Epidermis of newts given DMSO alone remained non-reactive to mAb WE3. When RA was given on days 7 and 10 after amputation, when a low level of mAb WE3 reactivity is already present in the wound epithelium, a considerable enhancement of mAb WE3 reactivity occurred through the next few days. No such enhancement was seen with DMSO alone. RA also greatly increased mAb WE3 reactivity in the wound epithelium of denervated limbs, in which case the wound epithelial reactivity to mAb WE3 is normally low. Retinol palmitate also increased mAb WE3 reactivity. The results raise the possibility that the WE3 antigen is a component of most if not all retinoid target tissues in newts. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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