  The $^{12}C(e,e'p)$ reaction is analyzed in a model which explicitly includes
final state interactions due to the coupling of the proton and neutron emission
channels. We find that the effects of the final state interactions due to
charge exchange reactions are important to get a good description of the
symmetry properties of the recently measured Mainz spectral functions. We
discuss the possible role the off-shell effects may play for the correct
interpretation of spectral functions at large positive missing momenta.
