gametogenetic

配偶子形成の

関: gametogenesis

WordNet

the development and maturation of sex cells through meiosis

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/23 11:28:46」(JST)

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Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitotic division of haploid gametogenous cells. For example, plants produce gametes through mitosis in gametophytes. The gametophytes grow from haploid spores after sporic meiosis. The existence of a multicellular, haploid phase in the life cycle between meiosis and gametogenesis is also referred to as alternation of generations.

In animals

Scheme showing analogies in the process of maturation of the ovum and the development of the spermatids, following their individual pathways. The oocytes and spermatocytes are both gametocytes. Ova and spermatids are complete gametes. In reality, the first polar body typically dies without dividing.

Animals produce gametes directly through meiosis in organs called gonads (testicle in males and ovary in females). Males and females of a species that reproduces sexually have different forms of gametogenesis

spermatogenesis (male)
oogenesis (female)

Stages

However, before turning into gametogonia, the embryonic development of gametes is the same in males and females.

Common path

Gametogonia are usually seen as the initial stage of gametogenesis. However, gametogonia are themselves successors of primordial germ cells. During early embryonic development, primordial germ cells (PGCs) from the dorsal endoderm of the yolk sac migrate along the hindgut to the gonadal ridge. They multiply by mitosis and once they have reached the gonadal ridge in the late embryonic stage, they are called gametogonia. Gametogonia are no longer the same between males and females.

Individual path

From gametogonia, male and female gametes develop differently - males by spermatogenesis and females by oogenesis. However, by convention, the following pattern is common for both:

Cell type	ploidy/chromosomes in humans	DNA copy number/chromatids in human^{[Note 1]}	Process
gametogonium	diploid (2N)/46	2C before replication, 4C after / 46 before, 46 X 2 after	gametocytogenesis (mitosis)
primary gametocyte	diploid (2N)/46	2C before replication, 4C after / 46 before, 46 X 2 after	gametidogenesis (meiosis 1)
secondary gametocyte	haploid (1N)/23	2C / 46	gametidogenesis (meiosis 2)
gametid	haploid (1N)/23	1C / 23
gamete	haploid (1N)/23	1C / 23

In gametangia

Fungi, algae and primitive plants form specialized haploid structures called gametangia where gametes are produced through mitosis. In some fungi, for example zygomycota, the gametangia are single cells on the end of hyphae and acting as gametes by fusing into a zygote. More typically, gametangia are multicellular structures that differentiate into male and female organs:

antheridium (male)
archegonium (female)

In flowering plants

In flowering plants, the male gamete is produced inside the pollen grain through the division of a generative cell into two sperm nuclei. Depending on the species, this can occur while the pollen forms in the anther or after pollination and growth of the pollen tube. The female gamete is produced inside the embryo sac of the ovule.

Notes

^ Sources are mixed when using this system of numbering. Some sources use the chromatid number when writing "n" rather than the ploidy number. Hence gametogonium and primary gametocyte would be "4n" rather than "2n" with "4c" for copies. The system used below has been determined by wikipedia consensus and should not necessarily be used as the definitive source on the issue.

English Journal

Cg-SoxE and Cg-β-catenin, two new potential actors of the sex-determining pathway in a hermaphrodite lophotrochozoan, the Pacific oyster Crassostrea gigas.

Santerre C1, Sourdaine P, Adeline B, Martinez AS.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.Comp Biochem Physiol A Mol Integr Physiol.2014 Jan;167:68-76. doi: 10.1016/j.cbpa.2013.09.018. Epub 2013 Oct 9.
Sex determination is poorly known in mollusks, lophotrochozoa and most hermaphrodites. In the oyster Crassostrea gigas, an irregular successive hermaphrodite, sex determination may occur at the end of a gametogenetic cycle to prepare the next cycle. To investigate further into these aspects we have
PMID 24120488

Gamete production patterns, ploidy, and population genetics reveal evolutionary significant units in hybrid water frogs (Pelophylax esculentus).

Pruvost NB1, Hoffmann A, Reyer HU.
Ecology and evolution.Ecol Evol.2013 Sep;3(9):2933-46. doi: 10.1002/ece3.687. Epub 2013 Jul 30.
The European water frog Pelophylax esculentus is a natural hybrid between P. lessonae (genotype LL) and P. ridibundus (RR). It reproduces through hybridogenesis, eliminating one parental genome from its germline and producing gametes containing the genome of the other parental species. According to
PMID 24101984

Responses of diploid and triploid Pacific oysters Crassostrea gigas to Vibrio infection in relation to their reproductive status.

De Decker S1, Normand J, Saulnier D, Pernet F, Castagnet S, Boudry P.
Journal of invertebrate pathology.J Invertebr Pathol.2011 Feb;106(2):179-91. doi: 10.1016/j.jip.2010.09.003. Epub 2010 Sep 15.
Several Vibrio species are known to be pathogenic to the Pacific oyster Crassostrea gigas. Survival varies according to pathogen exposure and high mortality events usually occur in summer during gametogenesis. In order to study the effects of gametogenetic status and ploidy (a factor known to affect
PMID 20833182

Japanese Journal

GAMETOGENETIC CELLS IN THE SEA STAR, ASTERINA MINOR(Cell Biology and Morphology)(Proceedings of the Sixty-Ninth Annual Meeting of the Zoological Society of Japan)

Yamagata A.
Zoological science 15(Supplement), 27, 1998-12-15
NAID 110003369722

ヒメトビウンカの卵寄生バチに関する研究 : III.Anagrus nr.flaveolus WATERHOUSEの寿命と産卵力.

大竹昭郎
日本生態学会誌 19(5), 192-196, 1969-10-01
ヒメトビウンカはイネ縞葉枯病の媒介こん虫として知られるが, その卵寄生バチの主要なものとしてAnagrus nr.flaveolus(ホソバネヤドリコバチ科)が挙げられる.ここでは, 26℃, 18時間照明という条件の下で観察されたこの種類の成虫の寿命と産卵力について報告する. 成虫の寿命には変異が大きかったが, 砂糖水をあてがった場合, 平均寿命は雌雄ともに約3日であった.平均産卵数は約23であ …
NAID 110001881392

放射線によるWs(pbg)遺伝子のNicotiana plumbaginifoliaよりN.tabacumの種間移行 : II.配偶子形成期の照射による遺伝子種間移行頻度の推定

丹羽勝
育種學雜誌 19(2), 84-88, 1969-04-30
Nicotiana tabacum(n=24)の1そろいの染色体に、N.plumbaginifoliaの染色体が1本付加されている系統を用いて、実験を行なった。この系統では、tabacumの劣性白子遺伝子(ws)がホモになっていて、付加されたplumbaginifoliaの染色体上には、wsに対する優性遺伝子(Ws(pbg))が座を占めている。付加された染色体は体細胞分裂の過程でしばしば失なわれる …
NAID 110001811957