This chapter discusses regeneration of missing parts, which is one of the most remarkable of biological phenomena. It remains one that embodies a number of genuinely unsolved questions for each of which there is no real understanding of the visible events in terms of genes and molecules. The first of these is the nature of the permissive conditions for regeneration. Why do some structures regenerate, while other apparently similar structures in related species do not? The second is the problem of cell lineage: to what extent does regeneration occur from reserve cells or stem cells; and to what extent from dedifferentiation and reprograming of existing tissue cells? The third is the issue of how a complex pattern of structures can be regenerated. For example, both the stump and the regenerate of a salamander limb contains muscles and cartilages, but the pattern of muscles and cartilages that regenerates in the new hand is quite different from that which was present at the cut surface. There are some partial answers to these problems, and in due course they will doubtless be solved at a molecular level by experimental biology. In the meantime, a useful perspective can be obtained by considering the evolution of regeneration, or at least by comparing what is known about regenerative abilities across the animal kingdom.
|Title of host publication||Heart Development and Regeneration|
|Editors||Nadia Rosenthal, Richard P. Harvey|
|Publisher||Elsevier Academic Press Inc|
|Number of pages||10|
|Publication status||Published - 2010|