Cell, which is non-motile, is carried to the oosphere by means of a pollen tube.
The eggcell or oosphere is a large cell containing a single large nucleus, and in the green plants the rudiments of plastids.
In some cases the region where the penetration of the male organ takes place is indicated on the oosphere by a hyaline receptive spot (Oedogonium, Vaucheria, &c.), or by a receptive papilla consisting of hyaline cytoplasm (Peronosporeae).
Mycelium present, antheridia with antherozoids, oogonium with single oosphere: Monoblepharidaceae.
The contents of the antheridium are not set free, but that organ penetrates the oogonium by means of a narrow outgrowth, the fertilizing tube, and a male nucleus then passes over into the single oosphere, which at first multinucleate becomes uninucleate before fertilization.