Sperm and Generative Cell

Abstract

The generative cell and sperm spend their natural lives encased by the vegetative cell. The generative cell is formed at the first division of the microspore and divides in the pollen grain or pollen tube to form two sperm cells. Thus, the generative cell is never “free” of the vegetative cell in which it is embedded. Sperm are similarly embedded in the vegetative cell of pollen grain or pollen tube, but are released from the pollen tube into the embryo sac, usually into the degenerating synergid. They are briefly free of the vegetative cell during which time they travel a short distance to the egg or central cell where they fuse with the female nuclei. In vivo, sperm release occurs spontaneously within the embryo sac, and free sperm cannot be collected for experimentation.