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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts | News Archive July 25, 2013

 

planaria regenerating head

Above: Reactivating head regrowth in a regeneration-deficient planarian species

Researchers at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden
discovered a crucial molecular switch in the flatworm that decides whether
a lost head can be regenerated or not.

Even more spectacular: The scientists manipulated the genetic circuitry of the
worm in such a way as to fully restore its regeneration potential.





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Heading for regeneration

Max Planck researchers manage to reactivate head regeneration in a regeneration-deficient species of planarian flat worms.

The rabbit can't do it, neither can a frog, but zebrafish and axolotls can and flatworms are true masters of the craft: Regeneration. Why some animals can re-grow lost body parts or organs while others cannot remains a big mystery. And even more intriguing to us regeneration-challenged humans is the question whether one might be able to activate regenerative abilities in species that don't usually regenerate.

Researchers at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden are now one step further in understanding the factors that regulate regeneration. They discovered a crucial molecular switch in the flatworm Dendrocoelum lacteum that decides whether a lost head can be regenerated or not. And what is even more spectacular: The scientists manipulated the genetic circuitry of the worm in such a way as to fully restore its regeneration potential.

Their research results appear in Nature, July 24, 2013.

In his lab, Jochen Rink, research group leader at the MPI-CBG, usually studies the flatworm species Schmidtea mediterranea. It is known for its excellent regenerative abilities and thus a popular model species in regeneration research:

"We can cut the worm to 200 pieces, and 200 new worms will regenerate from each and every piece," Rink explains. Now, for a change, Rink and colleagues brought a different beast into the lab, the flatworm Dendrocoelum lacteum. Even though a close cousin of the regeneration master S. mediterranea, this species had been reported to be incapable of regenerating heads from its posterior body half. "What's the salient difference between the two cousins," the researcher asked?

Together with researchers from the Center for Regenerative Therapies Dresden Rink's team searched for an answer amongst the genes of the two species, focusing on the so-called Wnt-signaling pathway. Like a cable link between two computers, signalling pathways transmit information between cells. The Dresden researchers inhibited the signal transducer of the Wnt pathway with RNAi and thus made the cells of the worm believe that the signalling pathway had been switched to "off". Consequently, Dendrocoelum lacteum were able to grow a fully functional head everywhere, even when cut at the very tail.

Re-building a head complete with brain, eyes and all the wiring in between is evidently complicated business. However, as the study showed, regeneration defects are not necessarily irreversible. Jochen Rink is stunned: "We thought we would have to manipulate hundreds of different switches to repair a regeneration defect; now we learned that sometimes only a few nodes may do."


Will this knowledge soon be applicable to more complex organisms – like humans, for example?

"We showed that by comparisons amongst related species we can obtain insights into why some animals regenerate while others don't – that's an important first step."


Original publication:
S.-Y. Liu, C. Selck, B. Friedrich, R. Lutz, M. Vila-Farré, A. Dahl, H. Brandl, N. Lakshmanaperumal, I. Henry & J. C. Rink Reactivating head regrowth in a regeneration-deficient planarian species

Nature, 25 July 2013

Original press release:http://www.mpg.de/7470432/planarian-regeneration