  Quark-lepton symmetry invites consideration of the existence of sterile
neutrinos. Long ago, we showed that this approach predicts large neutrino
mixing amplitudes. Using a Weyl spinor approach, we show, in an analytic
example, how this, and pseudo-Dirac pairing, can develop within a reduced rank
version of the conventional see-saw mechanism, from small intrinsic mixing
strengths. We show by numerical examples that mixing of active and sterile
neutrinos can affect the structure of oscillations relevant to extraction of
neutrino mixing parameters from neutrino oscillation data.
