Planarians, a type of flatworm, reproduce by asexual fission. Cut one in half, and the missing parts will regrow until you have two planarians. Scientists have known for a while that the regeneration took place among a cluster of cells called cNeoblasts. Some wondered if was possible to grow an entire worm from a single such cell, and so performed an experiment:
Wang and Reddien harvested a single cNeoblast from one type of planarian. Then they gave a different kind of planarian, one that did not have its own neoblasts and couldn’t regenerate, a lethal dose of radiation. Its tissues started to die, from the head down toward its tail. Then they implanted the first worm’s neoblast into the tail of the second, dying worm.
They watched as the transplanted cNeoblast multiplied, differentiated and “ultimately replaced all the host’s tissues,” according to a news release from the Whitehead Institute for Biomedical Research. Descendants of the single neoblast cell differentiated into neuronal, intestinal and other adult cell types, taking over the jobs of the host’s dying cells. The newly restored worm was an exact genetic copy of the cNeoblast donor. All this from one single cell.
http://www.popsci.com/science/article/2011-05/flatworm-regenerates-new-body-single-cell via GearFuse | Photo: Flickr user puuikibeach used under Creative Commons license