Fig. 4. Displacements of miscrospheres in the intranuclear region. (A) Typical MSD profiles of 100-nm diameter nanospheres in the intranuclear region. (B) Distribution of the MSDs of nanospheres embedded in the nucleus evaluated at a time-lag of 0.1 seconds. (Inset) Ensemble-averaged MSD of nanospheres embedded in the nucleus obtained by the sum of all MSDs and divided by the number of MSDs (n=84). (C) Size distribution of nuclear microdomains probed by particle nanotracking. The mean diameter is 290±50 nm (mean±s.d., n=84). (D) Mean diffusion coefficient, , of the nanospheres in the intranuclear region (n=84). At early time-points, D decreases with time, a sign for elastic trapping, whereas at later time-points, D becomes independent of time, a sign for viscous diffusion, albeit at a much slower pace than predicted by using the low interstitial viscosity measured by FRAP (see Discussion). The diffusion coefficient of the same nanospheres in water is constant and equals to 4.53 µm²/second.