  Density waves in the central kpc of galaxies, taking the form of spirals,
bars and/or lopsided density distributions, are potential actors of the
redistribution of angular momentum. They may thus play an important role in the
overall evolution of the central structures, not mentioning the possible link
with the active/non-active central mass concentration. I present here some
evidence for the presence of such structures, and discuss their importance in
the context of dynamical evolution.
