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© 2025. This work is published under http://creativecommons.org/licenses/by/4.0/ (the "License"). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Many examples of self-organized embryonic patterning can be attributed to chemically mediated systems comprising interacting morphogens. However, mechanical patterning also contributes to the emergence of biological forms. For example, various studies have demonstrated that diverse patterns arise from elastic instabilities associated with the constrained growth of soft materials, which generate wrinkles, creases and folds. Here, we show that between days 12 and 13 of in ovo development, transient experimentally increased activity of the sonic hedgehog pathway in the chicken embryo, through a single intravenous injection of smoothened agonist (SAG), abolishes the Turing-like chemical patterning of reticulate scales on the ventral footpad and promotes a transition to mechanical labyrinthine skin folding. Using in situ hybridization, nanoindentation and labelling of proliferating cells, we confirm that skin surface folding is associated with the loss of signalling placode pre-patterning as well as increased epidermal growth and stiffness. Using additional in ovo hydrocortisone treatments, we also demonstrate that experimentally induced hyper-keratinization of the skin mechanically restricts SAG-induced folding. Finally, we verify our experimental findings with mechanical growth simulations built from volumetric light sheet fluorescence microscopy data. Overall, we reveal that pharmacological perturbation of the underlying gene regulatory network can abolish chemical skin appendage patterning and replace it with self-organized mechanical folding.

Details

Title
Exacerbated sonic hedgehog signalling promotes a transition from chemical prepatterning of chicken reticulate scales to mechanical skin folding
Author
Cooper, Rory L; Jahanbakhsh, Ebrahim; Durán, Gabriel N Santos; Milinkovitch, Michel C
Pages
1-16
Section
Research
Publication year
2025
Publication date
2025
Publisher
The Royal Society Publishing
e-ISSN
20462441
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3202188631
Copyright
© 2025. This work is published under http://creativecommons.org/licenses/by/4.0/ (the "License"). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.