Fig. 3: Force-displacement measurements of C. elegans embryos.
From: Force microscopy of the Caenorhabditis elegans embryonic eggshell
a Representative micro-indentation loading curves (after baseline correction), i.e. measured force response Fz of the eggshell vs sensor tip indentation depth Δz, for untreated and treated eggs, including displacements beyond eggshell rupture. Fz increases in a nonlinear way with respect to Δz, indicating increasing an effective stiffness of the eggshell up to the puncture point. Force response to loading is strongest for untreated eggs (dark blue) and becomes very weak for bleach + chitinase-treated eggshells (light blue), where complete removal of the vitelline layer and the chitin layer is expected. Shell puncture events are marked as dotted circles in the plots. b The critical force value Fzpunct where eggshell puncture occurs is plotted vs the corresponding indentation depth Δzpunct, for different treatments and for all embryonic stages (gastrulation, bean and twitching stage). Fzpunct decreases drastically with the severity of the treatment. Very low values in the range of 0.5 μN are found after bleach + chitinase treatment, where only the innermost chondroitin proteoglycan layer of the eggshell remains. Untreated eggs can sustain the highest indentation depth Δzpunct, whereas the limit of eggshell deformation is lower but comparable after different treatments
