  Elasticity is a fundamental cellular property that is related to the anatomy,
functionality and pathological state of cells and tissues. However, current
techniques based on cell deformation, atomic force microscopy or Brillouin
scattering are rather slow and do not always accurately represent cell
elasticity. Here, we have developed an alternative technique by applying shear
wave elastography to the micrometer scale. Elastic waves were mechanically
induced in live mammalian oocytes using a vibrating micropipette. These audible
frequency waves were observed optically at 200,000 frames per second and
tracked with an optical flow algorithm. Whole cell elasticity was then mapped
using an elastography method inspired by the seismology field. Using this
approach, we show that the elasticity of mouse oocyte is decreased when the
oocyte cytoskeleton is disrupted with cytochalasin B. The technique is fast
(less than 1 ms for data acquisition), precise (spatial resolution of a few
micrometers), able to map internal cell structures, robust, and thus represents
a tractable novel option for interrogating biomechanical properties of diverse
cell types.
