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|Title:||Intercalary Regeneration in Larval Ambystoma Limbs: The Origin of Skeletal Structures and The Non-Segmental Organization of Morphogenetic Information|
|Author(s):||Pescitelli, Maurice Joseph, Jr.|
|Department / Program:||Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Urodele limbs are able to regulate for intercalary deletions created when distal regeneration blastemas are grafted to a more proximal level. Using several morphological markers, pigmentation differences between white and dark axolotls, and the difference in nucleolar number between diploid and triploid animals, I show that the entire intercalary regenerate is derived from the stump when wrist or tarsus blastemas are grafted to the mid-stylopodium of the fore- or hindlimb. The transplanted prospective autopodium forms no more than would be expected in situ. Thus, the rule of distal transformation is not violated during intercalary regeneration in salamanders.
It has been shown for mature insect appendages that the extent of intercalary regeneration is controlled by homologous, repeating segmental gradients. I have repeated the experiments which led to this conclusion on mature Ambystoma limbs to determine whether they behave in the same way as insect appendages in regard to intercalary regeneration. Fully-differentiated distal limb regions grafted to more proximal levels regenerate only the host segment, but the extent of this regeneration is a function of the limb segments which are combined, and not the intra-segmental levels. Thus, homologous, segmentally repeating gradients of morphogenetic information do not appear to exist in mature Ambystoma limbs. Rather, their morphogenetic information is organized in a continuous sequence of positional values.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2015-05-14|