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WonderRegeneration biology fact

Cut certain planarian flatworms into pieces, and each small fragment can regrow into a whole worm within days to weeks, complete with a head and tail at the right ends.

Planarian

BiologyScienceHealth

The story behind the card

Laboratory work focuses mostly on Schmidtea mediterranea and species of Dugesia. As early as 1898 the biologist Thomas Hunt Morgan found that a piece as small as 1/279 of a worm could regrow a whole animal; later estimates put the smallest working fragment at around 10,000 cells. The new tissue comes from neoblasts, adult stem cells spread throughout the body. In 2011 Peter Reddien's laboratory showed that a single transplanted neoblast could rebuild the tissues of a worm whose own stem cells had been destroyed by radiation. Chemical signals between cells, including the Wnt pathway that humans also have, tell each wound whether to grow a head or a tail. Planarians are now a leading model for research into how tissues might be made to repair themselves.

Türkçe oku
Bazı planarya (yassı solucan) türleri parçalara ayrıldığında, her küçük parça günler ya da haftalar içinde yeniden bütün bir solucana dönüşebilir. Baş ve kuyruk her seferinde doğru uçta çıkar.

Laboratuvarlarda en çok Schmidtea mediterranea ile Dugesia cinsinden türler incelenir. Biyolog Thomas Hunt Morgan daha 1898'de, solucanın 279'da biri kadar küçük bir parçasının bile bütün bir hayvana dönüşebildiğini buldu; sonraki tahminlere göre işe yarayan en küçük parça yaklaşık 10.000 hücreden oluşuyor. Yeni dokuyu, vücudun her yerine dağılmış erişkin kök hücreler olan neoblastlar üretir. 2011'de Peter Reddien'in laboratuvarı, kendi kök hücreleri ışınlamayla yok edilmiş bir solucana nakledilen tek bir neoblastın dokuları yeniden kurabildiğini gösterdi. İnsanda da bulunan Wnt adlı sinyal yolu gibi hücreler arası kimyasal sinyaller, her yaranın baş mı kuyruk mu üreteceğini belirler. Planaryalar bugün, dokuların kendini nasıl onarabileceğini araştıran çalışmaların başlıca modellerinden biridir.

Sources and further reading

Background reading: Planarian
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