gametophyte

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gametophyte

(gəmē`təfīt'), phase of plant life cycles in which the gametes, i.e., egg and sperm, are produced. The gametophyte is haploid, that is, each cell contains a single complete set of chromosomes, and arises from the germination of a haploid spore. In many lower plants, the gametophyte phase is the dominant plant form; for example, the familiar mosses are the gametophyte form of the plants. The alternate phase of the plant life cycle is the sporophyte, the diploid plant form, with each cell containing two complete sets of chromosomes. For example, in mosses the sporophyte is a capsule atop a slender stalk that grows out of the top of the gametophyte. The sporophyte develops from the union of two gametes, such as an egg fertilized by a sperm; in turn, the sporophyte forms spores that develop into gametophytes. The alternation between haploid gametophyte and diploid sporophyte phases, known as alternation of generations, occurs in all multicellular plants. As plants advanced in evolutionary development, the sporophyte became the increasingly dominant plant form and the gametophyte form has been correspondingly reduced. In contrast to mosses, for example, in the advanced angiosperms the male and female gametophytes are reduced to three-celled and seven-celled structures, respectively, found within the reproductive organs of the familiar flowering plant (the sporophyte). See also fertilizationfertilization,
in biology, process in the reproduction of both plants and animals, involving the union of two unlike sex cells (gametes), the sperm and the ovum, followed by the joining of their nuclei.
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; reproductionreproduction,
capacity of all living systems to give rise to new systems similar to themselves. The term reproduction may refer to this power of self-duplication of a single cell or a multicellular animal or plant organism.
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Gametophyte

 

sexual generation in those plants that exhibit alternation of generations. The gametophyte alternates in the development cycle with the asexual generation or sporophyte. In many plants the gametophyte carries on an autonomous existence, independent of the sporophyte. In some cases it is not distinguishable from the sporophyte by its external appearance (for example, the gametophyte in many algae); in others it is very distinct, for example, in the prothallia of ferns, horsetails, and lycopodia. In angiospermous plants the gametophyte is reduced to a pollen grain (male gametophyte) and to an embryo sac (female gametophyte). The gametophyte cell nuclei are characterized by half the number (haploid) of chromosomes in comparison to the cell nuclei of the sporophyte.

gametophyte

[gə′mēd·ə‚fīt]
(botany)
The haploid generation producing gametes in plants exhibiting metagenesis.
An individual plant of this generation.
References in periodicals archive ?
The gametophytic phase of Cheilanthes has been subject of abundant literature.
Antheridia developed on separate gametophytic prothalli, which were elongated and much longer than archegonial prothalli.
Haploids are sporophytes with the gametophytic chromosome number.
More specifically, this invention relates to the control of transgene transmission by male and/or female gametes or gametophytes using a gametophytic sterility trait.
Both gametophytic and sporophytic tissues from in vitro cultures were cryopreserved using the encapsulation-dehydration method (Fabre and Dereuddre, 1990), as well as using a method of drying without encapsulation, or "open drying.
S-RNase uptake by compatible pollen tubes in gametophytic self-incompatibility.
Compared gametophytic development of three species of Phebodium (Polypodiaceae, s.
This resemblance in ornamentation indicates that a similar patterned biosynthesis of sporopollenin is possible on an a-cellular sporophytic structure (pro-orbicule) as on a cellular gametophytic structure (microspore).
One potential source of morphological characters that is often overlooked is the gametophytic stage.
The dry type of stigma seems to be related to the sporophytic self-incompatibility systems, and the wet type of stigma to the gametophytic systems.
First, ferns and lycophytes have a unique life cycle that includes external fertilization during the gametophytic stage, requiring environmental liquid water (Raven et al.
Although it was shown that the resulting haploid individual inherits cytoplasm of female origin (Chase, 1963; Goodsell, 1961), it is not clearly established that such cytoplasm derives from the egg cell (Lacadena, 1974), so the possibility of a female gametophytic origin other than the egg cell should not be ruled out.