Textures for Neutrino Mass Matrices in Gauge Theories

We review previous work on neutrino mass textures in gauge theories. Such textures may arise as a result of flavour symmetries. In a given theory, it is possible to give a classification of heavy Majorana neutrino mass matrices, assuming the Dirac masses of the neutrinos to be of the same form as the ones of the up-quarks. Heavy Majorana neutrino mass matrices leading to large neutrino mixing, are tabulated as an example. Such solutions are now of interest, in the light of the Super-Kamiokande data.