  We study the nucleon contribution to the electromagnetic vertex function of
neutrinos that propagate in a matter background in the presence of a magnetic
field. Starting from the one-loop expression for the corresponding terms of the
vertex function, and taking into account the anomalous magnetic coupling of the
nucleons, we calculate the B-dependent part of the form factors that determine
the induced charge of the neutrino. A formula for the neutrino induced charge
is obtained, and it is evaluated for various illustrative situations. The terms
due to the nucleons can be important in some cases, depending on the physical
conditions of the environment.
