  We study the chemical evolution of Zr, La, Ce and Eu in the Milky Way discs
and bulge by means of chemical evolution models compared with recent
spectroscopic data. We consider detailed chemical evolution models for the
Galactic thick disc, thin disc and bulge, which have been already tested to
reproduce the observed [$\alpha$/Fe] vs [Fe/H] diagrams and metallicity
distribution functions for the three different components, and we apply them to
follow the evolution of neutron capture elements. In the [Eu/Fe] vs [Fe/H]
diagram, we observe and predict three distinct sequences corresponding to the
thick disc, thin disc and bulge, similarly to what happens for the
$\alpha$-elements. We can nicely reproduce the three sequences by assuming
different timescales of formation and star formation efficiencies for the three
different components, with the thin disc forming on a longer timescale of
formation with respect to the thick disc and bulge. On the other hand, in the
[X/Fe] vs [Fe/H] diagrams for Zr, La and Ce, the three populations are mixed
and also from the model point of view there is an overlapping between the
predictions for the different Galactic components, but the observed behaviour
can be also reproduced by assuming different star formation histories in the
three components. In conclusions, it is straightforward to see how different
star formation histories can lead to different abundance patterns and also
looking at the abundance patterns of neutron capture elements can help in
constraining the history of formation and evolution of the major Galactic
components.
