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#organ size

2 public questions tagged with this topic.

Regeneration -l

Which factor regulates organ size and regeneration in planaria?

Regenerative scaling requires coordination of growth and patterning to match body size. Notum-Wnt antagonistic balance achieves this: posterior muscle cells secrete Wnt ligands promoting proliferation of underlying neoblast progeny and posterior tail expansion, while anterior midline muscle secretes Notum deactivating Wnt locally limiting growth and allowing head differentiation. Negative feedback adjusts Wnt range ensuring proportional head-tail domains regardless of fragment size. Hedgehog modulates wnt expression but not size sensing, JAK-STAT influences stem cell maintenance and differentiation, Pax6 controls eye regeneration specifically. Thus Notum-Wnt ratio serves as scalable rheostat controlling both identity and organ size during regeneration.

Ref: Nature, Position control genes: Notum-Wnt balance regulates scaling and organ size in planarian regeneration.

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Cell Signaling Other Signaling Pathways

Hippo pathway primarily regulates

organ size and growth, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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