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Topic: Gametophyte

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	Gametophyte - Wikipedia, the free encyclopedia
		A gametophyte is the haploidor possibly diploid structure or phase of life of a sexually-reproducing plant.
		The gametophyte can be the dominant part of the plant's life cycle as in mosses, or very reduced as in ferns and flowering plants (angiosperms), where the female form (ovule) is known as a megagametophyte and the male form (pollen) is called a microgametophyte, the dominant phase of life for bryophytes (nonvascular plants).
		Gametophytes produce sperm and eggs through the process of mitosis since gametophytes are haploid cells, like sperm and egg.
	en.wikipedia.org /wiki/Gametophyte (207 words)

	Alternation of generations - Wikipedia, the free encyclopedia
		The life cycle of organisms with so-called "alternation of generations" is characterized by each phase consisting of two separate, free-living organisms: a gametophyte thallus or plant, which is genetically haploid, and a sporophyte thallus or plant, which is genetically diploid.
		All plants have diploid sporophyte and haploid gametophyte stages that are multicellular, and the differences between plant groups are in the relative sizes, forms, and trophic abilities of the gametophyte or sporophyte forms, as well as the level of differentiation in the gametophytes.
		Nontracheophyte plants including the liverworts, hornworts and mosses undergo an alternation of generations; the gametophyte generation is the most common.
	en.wikipedia.org /wiki/Alternation_of_generations (914 words)

	CERATOP3new
		Gametophyte size was estimated by measuring the width and length of the gametophyte and using these dimensions to calculate the area of an ellipse.
		Gametophytes were chosen by placing the point of a heat-sterilized dissecting needle into the culture using the naked eye, and then selecting the 10 gametophytes nearest to that point, except for the last day of sampling, where each plate was sampled for 5 small gametophytes and 5 large gametophytes nearest the point.
		Gametophytes in such cultures thus could not have been exposed to antheridiogen from the germination of the spore until the onset of the 2D exosporic stage if antheridiogens are secreted only by 2D exosporic gametophytes, as no 2D exosporic gametophytes were present at the time of spore germination.
	www.mc.edu /campus/users/rhamilto/CERATOP3new.html (3648 words)

	gametophyte -- Encyclopædia Britannica
		The female gametophyte is never released from the tree until the seed matures.
		The male gametophyte phase of the life cycle begins in the microsporangium with meiotic production of tetrads of microspores followed by the division of each haploid microspore into a three-celled pollen grain.
		The gametophytes of the vascular cryptogams mature after the spores that initiated them have been shed from the parent plant, so that the...
	www.britannica.com /eb/article-9035970 (565 words)

	gametophyte - Britannica Concise
		gametophyte - in certain plants, sexual phase (or an individual representing the phase) in the alternation of generations—a phenomenon in which two distinct phases occur in the life history of the plant, each phase producing the other.
		The male gametophyte is briefly separated from the sporophyte when pollen is released into the wind.
		The gametophytes of the vascular cryptogams mature after the spores that initiated them have been shed from the parent plant, so that the gametophytes are...
	concise.britannica.com /ebc/article-9365205 (543 words)

	Non-seed plants
		The protrusions on the surface are gemmae, antheridia, and archegonia.
		The horizontal plant with bumps (antheridia) is the gametophyte.
		The gametophytes may begin development within the cone before they are shot violently out of the cone to begin an independent existance.
	www.cas.vanderbilt.edu /bioimages/pages/non-seed-plants.htm (488 words)

	Bryophyta (Site not responding. Last check: 2007-10-20)
		The embryo grows and forms a mature sporophyte, within which sporogenous tissue will form spore tetrads, which in turn are released as the spores, forming either the gametophyte, or the protonema, which in turn forms the typical gametophyte.
		It absorbs water and nourishment from the gametophyte for the sporophyte.
		As the seta elongates, the old archegonium is torn from the gametophyte and remains on the capsule as the calyptra.
	www.cs.cuc.edu /~tfutcher/Bryophyta.html (706 words)

	gametophyte
		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 alternation between haploid gametophyte and diploid sporophyte phases, known as alternation of generations, occurs in all multicellular plants.
		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).
	www.factmonster.com /ce6/sci/A0820126.html (288 words)

	kingdoms
		Sporangia are borne in Sori of the fronds
		One multicellular body is haploid (1n) which is called the gametophyte generation and the second multicellular body is diploid (2n) which called the sporophyte generation.
		Gametophyte generation is inconspicuous inside of developing pine cones.
	www.lions.odu.edu /~knesius/bio109n/kingdoms.html (1411 words)

	William (Ned) Friedman - abstracts
		In Polygonum-type female gametophytes, two haploid female nuclei are incorporated into the central cell, and fusion of a sperm cell with the binucleate central cell produces a triploid endosperm with a complement of two maternal and one paternal genomes, characteristic of most angiosperms.
		Conversely, endosperm may represent the developmental transformation of the cellular phase of nonflowering seed plant female gametophyte ontogeny that was later sexualized by the addition of a second fertilization event in a strongly progenetic female gametophyte (endosperm homologous with a female gametophyte).
		The division of the generative cell in the male gametophyte of Ginkgo biloba to yield the sterile cell and the spermatogenous cell wall was examined in vivo and in vitro.
	spot.colorado.edu /~friedmaw/abstracts.html (9589 words)

	SparkNotes: The Life Cycle of Plants: Alternation of Generations
		The multicellular haploid plant structure is called the gametophyte, which is formed from the spore and give rise to the haploid gametes.
		The gametophyte comprises the main plant (the green moss or liverwort), while the diploid sporophyte is much smaller and is attached to the gametophyte.
		The haploid stage, in which a multicellular haploid gametophyte develops from a spore and produces haploid gametes, is the dominant stage in the bryophyte life cycle.
	www.sparknotes.com /biology/plants/lifecycle/section1.html (449 words)

	Liverworts
		The gametophytes, which range from approximately 0.15 mm to 2.5 cm in width and 2 mm to 25 cm in length, are mostly prostrate thallose or leafy forms.
		The gametophytes, whether thallose or leafy, are anchored to the substratum by microscopic hair-like, colorless rhizoids.
		Liverwort gametophytes, and indeed the gametophytes of all land plants, produce eggs and sperm.
	www.bio.umass.edu /biology/conn.river/liverwts.html (796 words)

	Bryophytes
		Gametophyte generation is the predominant and assimilative stage.
		The gametophytes may be unisexual or bisexual, depending on the species.
		The sporophyte is "horn-shaped", and grows from a basal sheath beneath the surface of the gametophyte thallus.
	scidiv.bcc.ctc.edu /rkr/Botany110/lectures/bryophytes.html (846 words)

	The four-celled female gametophyte of Illicium (Illiciaceae; Austrobaileyales): implications for understanding the ...
		In angiosperms with seven-celled female gametophytes, migration of one nucleus to the chalazal pole at the two-nucleate stage establishes a free-nuclear ontogeny within the chalazal domain that ultimately forms three antipodal cells and a polar nucleus.
		Female gametophytes of angiosperms are fundamentally modular structures in which individual developmental modules consist of "quartets" of nuclei.
		Conversely, in angiosperms with seven-celled female gametophytes, one of the nuclei migrates to the chalazal pole at the two-nucleate stage (two-headed arrow) initiating a second (chalazal) developmental module (in addition to the micropylar module) that ultimately forms three antipodal cells and a polar nucleus.
	www.amjbot.org /cgi/content/full/91/3/332 (6815 words)

	Alternation of Generations Table
		Gametophytes of nonseed tracheophytes are very tiny, but are free living (live separately from the parent sporophyte).
		Thus the sperm, instead of having to swim to the egg, is brought to the egg by the male gametophyte.
		The male gametophyte is the germinated pollen grain.
	science.kennesaw.edu /biophys/biodiversity/plants/plaltgen2.htm (1150 words)

	Characterization of Mutations That Feminize Gametophytes of the Fern Ceratopteris -- Strain et al. 159 (3): 1271 -- ...
		Characterization of Mutations That Feminize Gametophytes of the Fern Ceratopteris -- Strain et al.
		Characterization of Mutations That Feminize Gametophytes of the Fern Ceratopteris
		The male and hermaphroditic gametophytes of Ceratopteris are
	www.genetics.org /cgi/content/full/159/3/1271 (4498 words)

	Genetic Analysis of Female Gametophyte Development and Function -- Drews et al. 10 (1): 5 -- THE PLANT CELL
		gametophytic maternal mutants is dictated by the genotype of
		Buckner, B., and Reeves, S.L. (1994) Viability of female gametophytes that possess deficiencies for the region of chromosome 6 containing the Y1 gene.
		Lin, B.-Y. (1978) Structural modifications of the female gametophyte associated with the indeterminate gametophyte (ig) mutant in maize.
	www.plantcell.org /cgi/content/full/10/1/5 (5544 words)

	Biological Diversity 5
		Plants that produce bisexual gametophytes have those gametophytes germinate from isospores (iso=same) that are about all the same size.
		The haploid gametophyte phase is free-living and photosynthetic.
		The fern gametophyte has both sexes present and is referred to as a prothallium.
	www.emc.maricopa.edu /faculty/farabee/BIOBK/BioBookDiversity_5.html (2710 words)

	GYMNOSPERMS
		The archegonia in this gametophyte get fertilized by sperm from the male gametophyte and the zygote grows to produce an embryo which is enclosed in a seed coat of tissue from the parent plant.
		The sporangium breaks open to shed the immature gametophytes which are carried on the wind and may chance to arrive at a sporophyll on a female cone.
		Male gametophyte development has to wait up to a year for the female gametophyte to mature and produce two or three archegonia with egg cells.
	www.hcs.ohio-state.edu /hcs300/gymno.htm (1054 words)

	About ferns (Site not responding. Last check: 2007-10-20)
		The gametophyte is not the full fern, but a plant with only half the genetic material of the adult fern, rather like a sperm cell or an egg cell.
		The gametophyte is the intermediate stage from spore to adult fern.
		If the gametophyte finds itself in a suitably moist place, fertilisation takes place, and it is transformed into a complete adult plant.
	www.home.aone.net.au /byzantium/ferns/about.html (1723 words)

	SEEDLESS PLANTS (Site not responding. Last check: 2007-10-20)
		The Gametophyte of a moss is usually the largest and longest-lived generation of the moss life cycle.
		The Sporophyte consists of a Foot that anchors it to the gametophyte and a Stalk.
		Their Gametophytes, the Dominate Generation, are Green and Leafy and produce Archegonia and Antheridia.
	www.sirinet.net /~jgjohnso/seedless.html (1653 words)

	Evolution of Plants (Site not responding. Last check: 2007-10-20)
		The gametophyte generation in these (less primative) plants consists of only a few cells protected and nourished by the sporophyte generation (i.e., the gametophyte are not free living in gymnosperms and angiosperms).
		Note that this contrasts with the vascular plants in which the evolutionary trend is for the gametophyte to become profoundly nutritionally dependent on the sporophyte.
		Both male and female haploid gametophytes are reduced to small nonphotosynthetic structures housed entirely by the diploid sporophyte generation; thus, they embody the trend toward a dominant diploid phase.
	www.mansfield.ohio-state.edu /~sabedon/biol3060.htm (4045 words)

	Control of Male Gametophyte Development -- McCormick 16 (Supplement 1): S142 -- THE PLANT CELL
		gametophyte, or pollen grain, is a three-celled organism that
		Grini, P.E., Schnittger, A., Schwarz, H., Zimmermann, I., Schwab, B., Jurgens, G., and Hulskamp, M. Isolation of ethyl methanesulfonate-induced gametophytic mutants in Arabidopsis thaliana by a segregation distortion assay using the multimarker chromosome 1.
		Park, S.K., Howden, R., and Twell, D. The Arabidopsis thaliana gametophytic mutation gemini pollen1 disrupts microspore polarity, division asymmetry and pollen cell fate.
	www.plantcell.org /cgi/content/full/16/suppl_1/S142 (7163 words)

	Plant Diversity II: The Evolution of Seed Plants (Site not responding. Last check: 2007-10-20)
		The pollen grains… can be carried away by wind or animals after their release from the microsporangium… In seed plants, the use of resistant, far-traveling, airborne pollen to bring gametes together is a terrestrial adaptation that led to even greater success and diversity of plants on land.” p.
		This gametophyte generation associated with an embryonic sporophyte which in turn is protectively encased in desiccation-resistant capsules (derived from grandparental sporophyte tissue) we call seeds
		During the growth of the pollen tube, the male gametophyte completes its development by generating two sperm cells through mitotic division, and these two sperm cells are found within the cytoplasm of the pollen tube cell (the two sperm and pollen tube cell, all three cells, make up the male pine gametophyte)
	www.mansfield.ohio-state.edu /~sabedon/campbl30.htm (1729 words)

	Maize ROP2 GTPase Provides a Competitive Advantage to the Male Gametophyte -- Arthur et al. 165 (4): 2137 -- Genetics
		of functional redundancy in the male gametophyte is reduced.
		In pollen grains of both genotypes, the vegetative nucleus (vn) and the sperm nuclei (sn) exhibit characteristic diffuse and condensed morphologies, respectively.
		, 1999 Isolation of ethyl methanesulfonate-induced gametophytic mutants in Arabidopsis thaliana by a segregation distortion assay using the multimarker chromosome 1.
	www.genetics.org /cgi/content/full/165/4/2137 (6989 words)

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