Genetic specificity of induction:

mesenchyme may instruct the epithelium as to what sets of genes to activate, the responding epithelium can comply with these instructions only so far as its genome permits.

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#Id: 2371

#Unit 5. Developmental Biology

In regenerating planaria, β-catenin is activated in the posterior-facing blastema, which generates a tail.

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#Id: 2372

#Unit 5. Developmental Biology

 In planarian regeneration, an anterior polarity is dependent on repression of Wnt signaling, & allows head formation.

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#Id: 2373

#Unit 5. Developmental Biology

In regenerating planaria, Notum is activated in the anterior-facing blastema, which generates a head.

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#Id: 2374

#Unit 5. Developmental Biology

An anterior-to-posterior gradient of Erk signaling functions as a positive inducer of head specification

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#Id: 2375

#Unit 5. Developmental Biology

 Wnt signaling achieves its repression of head regeneration by inhibiting Erk

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#Id: 2376

#Unit 5. Developmental Biology

Regulation of the balance between Wnt and Notum signals underlie not only head-tail specification but also regulation of organ size.