  The coadjoint orbits for the series $B_l,\ C_l$ and $D_l$ are considered in
the case when the base point is a multiple of a fundamental weight. A
quantization of the big cell is suggested by means of introducing a
$\ast$-algebra generated by holomorphic coordinate functions. Starting from
this algebraic structure the irreducible representations of the deformed
universal enveloping algebra are derived as acting in the vector space of
polynomials in quantum coordinate functions.
