  We derive the two-plateau momentum distribution of final state (FS) quarks
produced in deep inelastic scattering (DIS) off nuclei in the saturation
regime. The diffractive plateau which dominates for small transverse momentum p
measures precisely the momentum distribution of quarks in the beam photon, the
role of the nucleus is simply to provide an opacity. The plateau for truly
inelastic DIS exhibits a substantial nuclear broadening of the FS momentum
distribution. We discuss the relationship between the FS quark densities and
the properly defined initial state (IS) nuclear quark densities.The
Weizs\"acker-Williams glue of a nucleus exhibits a substantial nuclear
dilution, still soft IS nuclear sea saturates because of the anti-collinear
splitting of gluons into sea quarks.
