  A gravitational scenario is proposed where the euclidean action is invariant
under the isotropic and homogeneous version of the euclidean {\it U(1)} group
of local transformations of the scale factor and scalar matter field,
interpreting the the trace of the second fundamental form as the gauge field.
The model allows spontaneous breakdown of some involved symmetries, including
possibly diffeomorphism invariance, and leads to the formation of topologiocal
deffects. In particular, we consider here the case of the wormhole-induced
formation of cosmic strings. (To appear in the Proceedings of the International
Workshop on "Quantum Systems: New Trends and Methods", World Scientific)
