  We report measurements on a Si-MOSFET sample with a slot in the upper gate,
allowing for different electron densities n_{1,2} across the slot. The dynamic
longitudinal resistance was measured by the standard lock-in technique, while
maintaining a large DC current through the source-drain channel. We find that
the conductance of the sample in a strong parallel magnetic field is asymmetric
with respect to the DC current direction. This asymmetry increases with
magnetic field. The results are interpreted in terms of electron spin
accumulation or depletion near the slot.
