  We report on the direct probing of the Fermi surface in the bulk of the
electron-doped superconductor Nd$_{2-x}$Ce$_x$CuO$_4$ at different doping
levels by means of magnetoresistance quantum oscillations. Our data reveal a
sharp qualitative change in the Fermi surface topology, due to translational
symmetry breaking in the electronic system which occurs at a critical doping
level significantly exceeding the optimal doping. This result implies that the
$(\pi/a,\pi/a)$ ordering, known to exist at low doping levels, survives up to
the overdoped superconducting regime.
