Two new papers put forward an alternative to an influential and popular model of the developmental mechanism that makes our upper arms different from our forearms or fingers.
Signals coming from a tissue called the apical ectodermal ridge (AER) are known to be important in limb development. In one long-standing model, these signals instruct cells of the upper arm to form first, then cells of the forearm, and finally cells of the hands.
In the 01 Aug ’02 issue of Nature (Vol. 418, No.6897, pp. 201-508 and pp. 539-544), two research groups propose instead that all these cell types are produced at the same time in the limb bud, and then - under the control of the AER - the regions of different cells expand at different times to form the complete limb. The groups are Gail R. Martin and colleagues of the School of Medicine, University of California at San Francisco, and Clifford J. Tabin of Harvard Medical School, Boston, and colleagues.
"There is little doubt that this confrontation of ideas will significantly advance the field," writes Denis Duboule of the University of Geneva, Switzerland, in an accompanying News and Views article.
Gail R. Martin
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Clifford J. Tabin
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(C) Nature press release.
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