Mechanical positional information, guiding the development of the dog’s nose makes the cover of Current Biology. The noses of many mammals, such as dogs, ferrets and cows, exhibit grooves forming a multitude of polygons bordered by creases that collect fluids and keep the nose wet. We show that differential growth of the skin tissue layers leads to the formation of domes, which are mechanically supported by the underlying blood vessels. This morphogenetic process, that we call ‘mechanical positional information’, could help explain the formation of other biological structures associated with blood vessels.
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On the cover: In this issue, Dagenais et al. demonstrate that the characteristic polygonal pattern of grooves on the noses of dogs, ferrets, and cows develops in the embryo via the mechanical coupling between epidermal folding and stiff blood vessels. Homogeneous growth of the epidermis makes it buckle into sharp creases exactly facing an underlying network of blood vessels because the latter form rigid base points—akin to stiff pillars supporting rising arches. These results suggest a new concept of “mechanical positional information” by which material properties of anatomical elements impose local constraints on an otherwise globally self-organized mechanical process. The resulting skin grooves retain physiological fluid, thereby keeping the nose wet and, among other effects, facilitating the collection of chemosensory molecules.
Image by Paule Dagenais, Fabrice Berger, and Michel C. Milinkovitch.
Much additional information is available in the original article:
Mechanical positional information guides the self-organized development of a polygonal network of creases in the skin of mammalian noses
Dagenais, Jahanbakhsh, Capitan, Jammes, Reynaud, De Juan Romero, Borrell & Milinkovitch
Current Biology 34, 5197–5212 (2024), doi.org/10.1016/j.cub.2024.09.055