Ectopic retinoic acid (RA) has been hypothesized to reprogram the positional identity of cells in developing and regenerating limbs to a single positional value corresponding to the posterior-ventral-proximal (PVPr) position on the limb. We tested this hypothesis by using RA to reprogram the information of blastema cells that were induced to form at different positions around the limb circumfer...

The wound epidermis is a transient secretory epithelium that apposes the mesenchymal blastema of a regenerating urodele limb, and is required for regeneration. Previous studies have shown that the positional identity of the blastema is respecified by retinoic acid (RA; Maden, M. (1982) Nature 295, 672-675), that the blastema contains RA (Scadding, S. R. and Maden, M. (1994) Dev. Biol. 162, 6086...

Inmetazoans, regeneration of lost body parts requiring the formation of a blastema is known as epimorphic regeneration. A blastema is composed primarily of two cell populations: an outer cell layer or ectoderm, derived from the epidermis that covers the wound surface after amputation/fission; and mesenchymal cells that proliferate and accumulate beneath this wound epidermis, eventually differen...

Nine surgically resected Wilms' tumors (WIT) and nude mouse heterotransplants from one WIT were studied by histochemistry and immunohistochemistry. Histochemistry showed acid phosphatase in all cells, while alkaline phosphatase and gamma-glutamyl transpeptidase were present in only some tubules. Using immunohistochemistry, antibodies to the intermediate filaments cytokeratin and vimentin distin...

Explants of 99 adult newt forelimb blastemata (21- to 24-day regenerates) were cultured, with and without implanted dorsal root ganglia, in modified Parker's medium (CMRL-1415) for periods of 72-144 h. Growth and differentiation of the cultured blastemata were compared with ganglionated and non-ganglionated controls fixed at the start of the culture period. The results of these experiments esta...

After limb amputation, urodele amphibians can regenerate lost parts perfectly throughout their life. However, Xenopus laevis shows its characteristic limb regenerative ability. Although Xenopus tadpole has the capacity to regenerate their limbs after amputation, after amputation of a froglet (a small frog after metamorphosis) limb, it can regenerate only a spike-shaped cartilage which has no pa...

Formation of a regeneration blastema following limb amputation is believed to occur through a process of dedifferentiation. It has been suggested, however, that the cells contributed to the blastema by the stump muscle are satellite-like cells, rather than cells originated by dedifferentiation. We have previously shown that simple epithelial keratins 8 and 18 are expressed in the mesenchymal pr...

After limb amputation, urodele amphibians can regenerate lost parts perfectly throughout their life. However, Xenopus laevis shows its characteristic limb regenerative ability. Although Xenopus tadpole has the capacity to regenerate their limbs after amputation, after amputation of a froglet (a small frog after metamorphosis) limb, it can regenerate only a spike-shaped cartilage which has no pa...

When imaginal disc fragments from Drosophila are cultured in adult female hosts, they either duplicate the part of the pattern specified by the fate map, or regenerate to replace the missing part. The new tissue is added by proliferation of a small number of cells from the cut edge, brought together when the wound heals to form a regeneration blastema. Specification of the new pattern has been ...