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Science Frontiers ONLINE No. 35: Sep-Oct 1984 |
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Caenorhabditis Elegans
The creature with this formidable name is only about a millimeter long and develops from egg to adult in about 3.5 days, at which time it possesses about 1,000 somatic cells. C. elegans is a roundworm, but a famous one. Its growth has been followed on a cell-bycell basis from egg to adult. The history of each cell is known from birth to death. The fact that C.elegans is nicely transparent helps the cell-watcher.
Here are some of the interesting things to be seen as cells proliferate, live, and die. First, C. elegans is bilaterally symmetrical, but the pattern of cell generation on the right differs from that on the left. Nevertheless, the creature ends up symmetrical, making one wonder where the directions for symmetry come from. Some cells are transients, dying when their jobs are done. A few doomed cells are generated only because they produce sister cells that are needed in the final animal. Such a programmed loss of cells may be a method of modifying an organism during evolution. John Sulston, one of the researchers, says, "Within the lineage you can see the fossil of its past."
(Marx, Jean L.; "Caenorhabditis Elegans: Getting to Know You," Science, 225:40, 1984.)
Comment. Sulston's statement reminds one of "Ontogeny recapitulates phylogeny," which we thought had been discredited long ago.