Stabilizing role of the basement membrane and dermal fibers during newt limb regeneration

Abstract

Background Following amputation of a newt limb, tissues at the amputation site undergo histolysis to give rise to a growth bud, or blastema, but they also provide a base on which the regenerate is constructed. Studies suggest that dermal tissues may differentially resist histolysis. Methods and Results To examine stability of tissues at the amputation site, more than 80 preblastemal staged regenerating limbs were examined histologically. Initially, all soft tissues not attached to bone retracted and were covered by migrating epithelium. The dermis was seen to be stable during the first week postamputation. Muscle dedifferentiated and was heavily stained with anti‐tenascin antibodies, but the intact overlying dermis was unstained. Fiber bundles, revealed by staining with phosphotungstic acid hematoxylin, isolated the dermis from dedifferentiating deeper tissues during the first week postamputation, but partially broke down during the second week. However, the basement membrane (BM) remained as the distalmost intact structure at the amputation site in all limbs examined. The BM was the foundation for new BM synthesis which preceded dermis synthesis in the base of the blastema during the second week, even while undifferentiated cells were accumulating centrally. Conclusions We suggest that the dermis resists histolysis long enough for new BM to form in continuity with that of the stump. Dermis formation (dermogenesis) distal to the amputation plane begins early as in mammalian healing but is not completed until after blastema formation. Thus, factors that inhibit dermal closure appear to distinguish regenerating from non‐regenerating appendages. © 1996 Wiley‐Liss, Inc.

Extent of ossification at the amputation plane is correlated with the decline of blastema formation and regeneration inXenopus laevis hindlimbs

“… a References: 1 Abdel‐Karim et al (1990); 2 Anton et al (1988); 3 Cannata et al (1992); 4 Christensen and Tassava (2000); 5 Filoni and Paglialunga (1990); 6 Filoni et al (1995); 7 Globus and Liversage (1975b); 8 Iten and Bryant (1973); 9 Korneluk et al (1982); 10 Korneluk and Liversage (1984); 11 Liversage et al (1987); 12 Liversage and McLaughlin (1983); 13 Liversage and Schotté (1992); 14 McLaughlin and Liversage (1986); 15 Neufeld et al (1996); 16 Peadon and Singer (1966); 17 Schotté and Butler (1941); 18 Singer (1952); 19 Stocum (1996a); 20 Tank et al (1976); 21 Tassava and Mescher (1975); 22 Tschumi (1957); 23 Young et al (1985). …”

“…Since the presence of a full thickness basement membrane underneath the AEC at initial early bud blastema formation would most likely block potential communication between the regenerate epithelium and blastemal mesenchyme, the increased presence of basement membrane in blastemas at early bud stage would predict that the animals at these stages have a difficult time maintaining an active AEC‐mesenchyme signaling relationship during regeneration (Neufeld et al, 1996). Lack of dermis beneath the wound epithelium appears to be another soft tissue adaptation to most directly allow signaling between the AEC and mesenchyme (Tschumi, 1957).…”

“…Lack of dermis beneath the wound epithelium appears to be another soft tissue adaptation to most directly allow signaling between the AEC and mesenchyme (Tschumi, 1957). Another dermal adaptation showing that the AEC is different from ordinary skin is the lack of skin glands in the blastema (Neufeld et al, 1996). Presence of these glands indicates skin that is attempting to function as normal skin, which cannot function in regeneration.…”

“…Shortly after amputation, the limb undergoes wound healing, in which epithelial tissue around the cut edge of the stump migrates to cover the surface of the wound (Singer, 1952). This epithelium is unique in character when compared to adult epithelial tissue, because it lacks underlying dermis and dermal skin glands (Tschumi, 1957; Tassava and Mescher, 1975; Korneluk et al, 1982; Liversage and McLaughlin, 1983; Neufeld et al, 1996; Christensen and Tassava, 2000), and the underlying basement membrane is incomplete and not clearly visible (Korneluk et al, 1982; Young et al, 1985; Neufeld et al, 1996). During and shortly after this healing event, the regeneration‐capable amputee undergoes a process of dedifferentiation, in which the muscle, skeletal, and other connective tissues revert to undifferentiated mesenchyme (Iten and Bryant, 1973; Tank et al, 1976; Korneluk and Liversage, 1984; Anton et al, 1988; Liversage and Schotté, 1992).…”

Temporal requirement for bone morphogenetic proteins in regeneration of the tail and limb of Xenopus tadpoles

“…While regeneration shows many parallels with ontogeny, there are some different processes involved. Regeneration-competent wound healing is generally rapid and involves covering the wound surface with a specialised epidermis that lacks an underlying dermis and basement membrane (Neufeld et al, 1996;Tschumi, 1957). Following wound healing, the differentiated cells of the stump must dedifferentiate and reenter the cell cycle, or else reserve stem cell populations must be mobilised and recruited to the wound site.…”