Thursday, December 12, 2013

The champion body grower

In my article on Oct 28 this year, I talked about achieving enormous life spans, like 1000 years. I mentioned that we need to learn to regenerate organs, if we want to live to be a thousand. Today we will talk about some interesting examples of regeneration, but in animals.
There are many characters in our mythology who could regrow cut limbs and even heads. The Greek mythological hero Prometheus could regrow liver. Hollywood and Bollywood films are ripe with humans and robots who regain cut body parts within no time. Organ regeneration seems to be everyone’s favorite fantasy.
We humans have a few regenerative capabilities ourselves. We heal from wounds and grow new skin. Our Livers can regrow after they are damaged. Liver donors can offer up to half of their livers to the needy and regrow it. But these abilities are a mere nothing when compared to what some animals can do.
Everybody has seen a lizard discarding her tail when attacked by a cat. The cat is fooled by the writhing tail. While it is watching the tail keenly, the lizard escapes. It can grow the tail back, ready to fool the next cat.
Similarly, cockroaches and salamanders can grow a cut leg. Lobsters have similar skills. Snails can even regrow their head!
But everything pales in front of the real champion regenerator – Planarian.
Planarian are a kind of flatworms. They live in freshwater. Most are very small, about a centimeter, but some grow to be a foot long. You can easily find great pictures of them on internet – search ‘Planarian images’ on Google.
If we cut a planarian in half, each part will grow to be a complete planarian in a week or two. You can cut them in four, and four planarian will be created. If you are a avid cutter, you can cut them into up to 279 pieces, and you will get a healthy population of 279 planarians.
Amazing, isn’t it? How can they do it? Planarians have a large stock of cells called Stem Cells. Stem Cells are basically unbranded cells. They are not skin cells, nor muscles nor anything else. They can become any other type of cells. Our growth as Embryos uses these cells. (See my November 29, 2013 article on Development).
When a planarian is cut, stem cells gather around the cut. They convert into the right kind of cells for that place. This continues till the whole body is built.
This astounding ability of planarian is extremely useful for scientists to understand regeneration of organs in humans. Studies are going on in universities all over the world to study this mechanism and apply it to growing human organs.
How old is the oldest planarian? No one knows. But it might help us to live to be a thousand.

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