Scale invariance of mechanical properties in the developing mammalian retina

Neuronal tissues form through physical forces guiding neuron movements. In the mammalian retina, events like neuron translocation occur over hours. How mechanical stresses induce tissue organisation at this timescale has remained unclear due to the inaccessibility of living retina tissue for in situ mechanical interrogation. Previous studies captured responses at second timescales or shorter. Here, we probed tissue mechanics in an in vitro model of the developing retina using magnetic droplets in mouse stem cell-derived retina organoids. We recorded strain responses to stress across four orders of magnitude in time, up to one hour. Dynamic creep compliance and tensile moduli followed a power law with an exponent consistent with a material just above the glass transition. Our findings suggest that neuronal tissue remodels in a scale-free manner while maintaining solid-like properties. Our measurements could open the door to understanding how mechanical signals drive connectivity in the central nervous system.