EN
In Galanthus nivalis during the progamic phase, both the embryo sac and somatic cells of the ovule change their ultrastructure and physiology, as observed by light, fluorescence, and electron microscopy. Fresh ovules from buds, opening flowers, and from cross-pollinated flowers were stained in toto to detect pectins, acidic polysaccharides, proteins, lipids, callose, free calcium ions and membrane-bound calcium. These substances were found only in the micropylar part of fertile ovules. All stainings were negative in sterile ovules. In EM, the somatic cells in the micropylar part of the ovule were observed to develop secretion activity. Their exudates passed to the intercellular spaces, mainly to the micropylar canal. The amount of the exudate increased after pollination. Free or loosely bound calcium ions were present in extracellular regions of the micropylar part of fertile ovules. The substances detected in the micropylar exudate of fertile ovules are suggested to support and direct pollen tube growth to the embryo sac.