Pronunciation: o-O-ga-mus

Etymology: Oogamous is derived from two Greek roots that mean egg (oion, οιον) and sexual union (gamos, γάμος). It means that the sexual union occurs by means of an egg (and by extention, a sperm).

Oogamous (adj) describes sexual reproduction in which the gametes are structurally very different. Usually oogamy means a large nonmotile egg and a small motile sperm (the sperm of the rhodophytes is nonmotile).

Note the egg (large gamete) and the tiny motile egg in the photo below.

By Jack R. Holt. Last revised: 01/02/2009