The Mass-Metallicity relation in galaxies of different morphological
  types
  By means of chemical evolution models of different morphological types, we
study the mass-metallicity (MZ) relation and its evolution with redshift. Our
aim is to understand the role of galaxies of different morphological types in
the MZ relation at various redshift. One major result is that at high redshift,
the majority of the galaxies falling on the MZ plot are apparently
proto-ellipticals. Finally, we show some preliminary results of a study of the
MZ relation in a framework of hierarchical galaxy formation.
