  Neutrino Majorana masses and mixings can be generated from a dimension-5
operator within the standard model particle content. After a review of the
mechanism of radiative enhancement of the mixing angle in a two-neutrino case,
we consider three-flavour mass matrices of two-zero texture generated from such
an operator and investigate the possibility of implementing the mechanism here.
We observe that radiative magnification of only the solar angle is consistent
with oscillation data on masses and mixings, and that too for nearly degenerate
neutrinos, with two of them having opposite CP parities, while for hierarchical
masses the mechanism does not work. In supersymmetry or in an extra-dimensional
scenario the above features are qualitatively unchanged.
