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By inverting triploid blastemas onto diploid stumps (and vice versa) the cellular contributions to supernumerary limbs so generated have been assessed. The four classes of 180 degrees supernumerary limbs each had a different mixture of stump and blastemal cells. The mesoderm of normal supernumeraries was composed entirely or almost entirely of stump cells(More)
To investigate whether the uniqueness of proximal and distal limb regenerates could be attributed simply to differing blastemal growth characteristics, their increase in volume, cell number and cell-cycle times were determined. With respect to these parameters proximal and distal blastemas were identical and, furthermore, no evidence could be found for the(More)
The model proposed in the preceding paper (Meinhardt, 1983) makes specific predictions about the handedness of supernumerary limbs generated after 180 degrees rotation of blastemas. These predictions are tested here by re-examining, in detail, the structure of 100 of these supernumeraries. Of the four predictions, only one was found not to hold. The other(More)
Various experiments were performed on the limb buds of axolotls to compare the behaviour of amphibian limbs with that previously reported for chick limbs. Following removal of the tip or whole limb bud, extensive powers of regulation were observed since complete limbs always formed. Similarly after distal to proximal grafts intercalary regulation occurred(More)
The regulative ability of the regeneration blastema has been studied by the technique of partial irradiation. Longitudinal halves of fore- and hindlimbs were irradiated and the product of regeneration from the unirradiated halves characterized. Such half irradiated limbs could regulate only to a very limited extent. In the upper arms the anterior halves(More)
An extensive series of skin grafting operations has been performed to investigate axial organization in the regenerating axolotl limb. Semicircular cuffs of skin from either anterior, posterior, dorsal or ventral surfaces were exchanged between right and left limbs thereby creating limbs with double anterior, double posterior, double dorsal or double(More)