Doubrovinski, K. et al. Proc. Natl. Acad. Sci. USA 114, 1051–1056 (2017).
Serwane, F. et al. Nat. Methods 14, 181–186 (2017).
The viscoelastic properties of cells have been studied extensively, and measuring these properties in tissues or organisms has now become possible as well. Doubrovinski et al. and Serwane et al. inject ferrofluidic droplets (which can be manipulated with a magnetic field) into their subjects and manipulate the droplets using external magnets. In the former study, the researchers dragged the droplets through cellularizing Drosophila embryos and inferred the viscoelastic properties of different regions based on the movement of the droplets. These measurements showed that the actin cytoskeleton confers elasticity to the cellular cortex, while the cytoplasm behaves in a viscous fashion. In Serwane et al., the researchers monitored the deformation of the droplets upon application of a magnetic field and found that viscoelasticity varies throughout the zebrafish tailbud.