Embryoid structures showing epidermal layers have been regenerated from isolated Vitis microspores. Experiments were carried out on 8 genotypes of Vitis including different donor plant growth conditions, chilling of microspores (4 °C), heat shock (35 °C) and colchicine exposure (10, 25 and 50 mg/l) as induction treatments and incubation of the cultures on 87 different solid and liquid NN and LS media. The reactions of the cultured microspores included enlargement and thickening of the exine, formation of microcalli, calli, globular proembryos and embryoid structures displaying cell differentiation. Callus formation took place mainly on solid LS media with 3 % or 12 % sucrose, whereas most of the embryoids developed on NN media with 3 % sucrose. Both, callus and embryoid formation, were promoted by colchicine treatment. 8 months after transfer of calli and embryoids to subculture media, 4 embryoids still showed cell proliferation
