gamete

gamete A specialized haploid cell (sometimes called a sex cell) whose nucleus and often cytoplasm fuses with that of another gamete (from the opposite sex or mating type) in the process of fertilization, thus forming a diploid zygote. In the lower plants the male gamete is a motile antherozoid, which needs water as a medium in which to move, similar to the spermatozoon in animals, and the female gamete is contained in the archegonium. In higher plants the male gamete is contained in the male gametophyte (microspore) and the female gamete is contained in the female gametophyte (megaspore); fertilization takes place only after the gametophytes come into contact (pollination) and the male gamete can be released without having to leave the plant. This adaptation, permitting fertilization in the absence of water, is analagous to internal fertilization in animals, and, like internal fertilization of animals, is an adaptation to dry environments. Usually there are many small male gametes, but only a few or one female gamete.

gamete (gam-eet) n. a mature sex cell: the ovum of the female or the spermatozoon of the male. Gametes are haploid, containing half the normal number of chromosomes.

gamete A reproductive cell that fuses with another gamete to form a zygote. Examples of gametes are ova and spermatozoa. Gametes are haploid, i.e. they contain half the normal (diploid) number of chromosomes; thus when two fuse, the diploid number is restored (see fertilization). Gametes are formed by meiosis. Gametes often differ in size, the smaller (usually male) gamete being known as the microgamete and the larger (usually female) as the macrogamete. See also sexual reproduction.