  We construct a supersymmetric $SO(10) \times U(1)_F$ model of the Yukawa
interactions at the grand unification scale from knowledge of a
phenomenological set of mass matrices obtained by a previous bottom-up
approach. The $U(1)_F$ family symmetry determines the textures for the Majorana
and generic Dirac mass matrices, while the $SO(10)$ symmetry relates each
particular element of the up, down, neutrino and charged lepton Dirac matrices.
The dominant second and third family contributions in the Dirac sector are
renormalizable, while the remaining contributions to the Dirac mass matrices
are of higher order, restricted by the $U(1)_F$ family symmetry to a small set
of tree diagrams, and mainly complex-symmetric. The tree diagrams for the
Majorana mass matrix are all non-renormalizable and of progressively
higher-order, leading to a nearly geometrical structure. Pairs of ${\bf 1, 45,
10}$ and ${\bf 126}$ Higgs representations enter with those having large vacuum
expectation values breaking the symmetry down to $SU(3)_c \times SU(2)_L \times
U(1)_Y$ near the grand unification scale. In terms of 12 parameters expressed
as the Yukawa couplings times vacuum expectation values for the Higgs
representations employed, a realistic set of 15 quark and lepton masses
(including those for the 3 heavy righthanded Majorana neutrinos) and 8 mixing
parameters emerges for the neutrino scenario involving the non-adiabatic
conversion of solar neutrinos and the depletion of atmospheric muon-neutrinos
through oscillations into tau-neutrinos.
