Study
Why polyps regenerate and we don't: Towards a cellular and molecular framework for Hydra regeneration
Bosch, Thomas C. G.
Developmental Biology, 2007
A review of regeneration in Hydra: the continuous turnover of its cells, the organiser region at the head end, the behaviour of dissociated cells reaggregated into a mass, and what distinguishes this from the regeneration seen in animals with more complex bodies.
- Studied in
- Hydra
- Sample size
- review of Hydra regeneration and tissue dynamics
Hydra maintains continuous cell turnover, with the whole animal effectively replaced on a timescale of weeks, so regeneration is an extension of normal maintenance rather than a special response. A head organiser establishes polarity; dissociated cells reaggregated into a pellet can reorganise into a complete animal. Regeneration proceeds largely by repatterning existing tissue rather than by proliferation.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Hydra regeneration is best understood as continuous developmental patterning that never switches off, rather than as a wound-triggered programme.
How NatureHQ reads it
Hydra is where "regeneration" stops being a useful single word. This animal is not repairing damage; it is permanently under construction, replacing itself continuously, and cutting it in half simply interrupts a process already running. That is a third category alongside the salamander's growth from a blastema and the planarian's rescaling of existing tissue. It also explains why Hydra appears in "immortal animal" lists — a body that is continuously rebuilt does not accumulate ageing in the usual way — and why that is a fact about tissue turnover rather than about not dying.
- A review of an animal with an unusually simple body plan; the extension to complex animals is by contrast rather than by continuity.
- The relationship between continuous turnover and regeneration is argued rather than demonstrated by a single experiment.
- Molecular detail has advanced substantially since.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Elsevier journalsPublished in an Elsevier journal.
doi.org/10.1016/j.ydbio.2006.12.012
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.