  Dynamical symmetry breaking in an expanding nuclear system is investigated in
semi-classical and quantum framework by employing a collective transport model
which is constructed to mimic the collective behavior of expanding systems. It
is shown that the fluctuations in collective coordinates during the expansion
are developed mainly by the enhancement of the initial fluctuations by the
driving force, and that statistical and quantum fluctuations have similar
consequences. It is pointed out that the quantal fluctuations may play an
important role in the development of instabilities by reducing the time needed
to break the symmetry, and the possible role of quantal fluctuations in
spinodal decomposition of nuclei is discussed.
