zygote

The product of the fusion of two gametes, before it has undergone mitosis or meiosis. In lower algae and fungi it may retain the motile nature of the gametes. More usually the zygote is immobile and may develop a thickened resistant wall to form a *zygospore. In higher plants the zygote is typically protected by maternal tissue, and divides immediately after fertilization forming a *proembryo. See also sexual reproduction.