WordNet

the female reproductive cell; the female gamete (同)egg_cell
small room in which a monk or nun lives (同)cubicle
a device that delivers an electric current as the result of a chemical reaction (同)electric cell
a room where a prisoner is kept (同)jail cell, prison cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
any small compartment; "the cells of a honeycomb"
a small unit serving as part of or as the nucleus of a larger political movement (同)cadre
throw eggs at
animal reproductive body consisting of an ovum or embryo together with nutritive and protective envelopes; especially the thin-shelled reproductive body laid by e.g. female birds
oval reproductive body of a fowl (especially a hen) used as food (同)eggs
coat with beaten egg; "egg a schnitzel"
the base of the natural system of logarithms; approximately equal to 2.718282...

PrepTutorEJDIC

卵,卵子
ovumの複数形
(刑務所の)『独房』;(修道院の)小さい独居室 / (ミツバチの)みつ房,巣穴 / 小さい部屋 / 『細胞』 / 電池 / 花粉室 / (共産党などの)細胞
『卵』,卵細胞 / 鳥の卵;(特に)鶏卵 / 《英話》《形容詞を伴って》(…な)やつ / 《俗》爆弾,手投げ弾
〈人〉‘を'扇動(激励)する;〈人〉‘を'そそのかして…させる《+『名』+『on to』 do》

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/07/17 15:34:03」(JST)

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Diagram of a human egg cell

The Egg cell is the female reproductive haploid cell (gamete) in oogamous organisms. The egg cell is typically not capable of active movement, and it is much larger than the motile sperm cells. When egg and sperm fuse, a diploid cell (the zygote) is formed, which gradually grows into a new organism.

Animals[edit]

In animals, egg cells are also known as ova (singular ovum, from the Latin word ovum meaning egg or egg cell). The term ovule is used for the young ovum of an animal. In higher animals, ova are produced by female gonads (sexual glands) called ovaries and all of them are present at birth in mammals and mature via oogenesis.

Human and mammal ova[edit]

Ovum and sperm fusing together

The process of fertilizing an ovum (Top to bottom)

In viviparous animals (which include humans and all other placental mammals), the ovum is fertilized inside the female body.

The human ova grow from primitive germ cells that are embedded in the substance of the ovaries. Each of them divides repeatedly to give rise to several smaller cells, the oogonia. The oogonia then develop via meiosis into the ova, the primary oocytes, and the polar bodies.^[1]

Once the ovum has been fertilized, it begins to divide over the course of a few hours or days, becoming a morula. The morula enters the uterine cavity where it is immersed in the secretions of the uterine glands, ultimately forming a blastocyst.^[2]

The ovum is one of the largest cells in the human body, typically visible to the naked eye without the aid of a microscope or other magnification device. The human ovum measures approximately 0.12 mm in diameter.^[3]

Ooplasm[edit]

Ooplasm (also: oöplasm) is the yolk of the ovum, a cell substance at its center, which contains its nucleus, named the germinal vesicle, and the nucleolus, called the germinal spot.^[4]

The ooplasm consists of the cytoplasm of the ordinary animal cell with its spongioplasm and hyaloplasm, often called the formative yolk; and the nutritive yolk or deutoplasm, made of rounded granules of fatty and albuminoid substances imbedded in the cytoplasm.^[4]

Mammalian ova contain only a tiny amount of the nutritive yolk, for nourishing the embryo in the early stages of its development only. In contrast, bird eggs contain enough to supply the chick with nutriment throughout the whole period of incubation.^[4]

Ova development in oviparous animals[edit]

In the oviparous animals (all birds, most fishes, amphibians and reptiles) the ova develop protective layers and pass through the oviduct to the outside of the body. They are fertilized by male sperm either inside the female body (as in birds), or outside (as in many fishes). After fertilization, an embryo develops, nourished by nutrients contained in the egg. It then hatches from the egg, outside the mother's body. See egg (biology) for a discussion of eggs of oviparous animals.

The egg cell's cytoplasm and mitochondria are the sole means the egg is able to reproduce by mitosis and eventually form a blastocyst after fertilization.

Ovoviviparity[edit]

There is an intermediate form, the ovoviviparous animals: the embryo develops within and is nourished by an egg as in the oviparous case, but then it hatches inside the mother's body shortly before birth, or just after the egg leaves the mother's body. Some fish, reptiles and many invertebrates use this technique.

Plants[edit]

All land plants have alternating diploid and haploid generations. Gametes are produced by the gametophyte, which is the haploid generation. The female gametophyte produces structures called archegonia, and the egg cells form within them via mitosis. The typical bryophyte archegonium consists of a long neck with a wider base containing the egg cell. Upon maturation, the neck opens to allow sperm cells to swim into the archegonium and fertilize the egg. The resulting zygote then gives rise to an embryo, which will grow into a new diploid individual (sporophyte). In seed plants, the archegonia are formed inside a structure called ovule, which contains the female gametophyte. After fertilization, the ovule develops into a seed containing the embryo.^{[citation needed]}

In flowering plants, the female gametophyte has been reduced to just eight cells referred to as the embryo sac inside the ovule. The gametophyte cell closest to the micropyle opening of the embryo sac develops into the egg cell. Upon pollination, a pollen tube delivers sperm into the embryo sac and one sperm nucleus fuses with the egg nucleus. The resulting zygote develops into an embryo inside the ovule. The ovule in turn develops into a seed and in many cases the plant ovary develops into a fruit to facilitate the dispersal of the seeds. Upon germination, the embryo grows into a seedling.^{[citation needed]}

Gene expression pattern determined by histochemical GUS assays in Physcomitrella patens. The Polycomb gene FIE is expressed (blue) in unfertilised egg cells of the moss Physcomitrella patens (right) and expression ceases after fertilisation in the developing diploid sporophyte (left). In situ GUS staining of two female sex organs (archegonia) of a transgenic plant expressing a translational fusion of FIE-uidA under control of the native FIE promoter

In the moss Physcomitrella patens, the Polycomb protein FIE is expressed in the unfertilised egg cell (Figure, right) as the blue colour after GUS staining reveals. Soon after fertilisation the FIE gene is inactivated (the blue colour is no longer visible, left) in the young embryo. ^[5]

Other organisms[edit]

In algae, the egg cell is often called oosphere.

References[edit]

^ "The Ovum in Gray's Anatomy". Retrieved 2010-02-16. .
^ Regan, Carmen L. (2001). "Pregnancy". In Worell, Judith. Encyclopedia of Women and Gender: Sex Similarities and Differences and the Impact of Society on Gender, Volume 1. Academic Press. p. 859. ISBN 9780122272455.
^ Search result of "120 micrometers" in Level O Biology - Google books
^ ^a ^b ^c "The Ovum". Gray's Anatomy. Retrieved 2010-10-18.
^ Assaf Mosquna, Aviva Katz, Eva L. Decker, Stefan A. Rensing, Ralf Reski, Nir Ohad (2009): Regulation of stem cell maintenance by the Polycomb protein FIE has been conserved during land plant evolution. Development 136, 2433-2444. doi:10.1242/10.1242/dev.035048

External links[edit]

The Ovarian Kaleidoscope Database description of 1800 genes involved in ovarian functions

UpToDate Contents

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English Journal

Small RNAs in spermatogenesis.

Yadav RP, Kotaja N.SourceDepartment of Physiology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland. Electronic address: ramprakash.yadav@utu.fi.
Molecular and cellular endocrinology.Mol Cell Endocrinol.2014 Jan 25;382(1):498-508. doi: 10.1016/j.mce.2013.04.015. Epub 2013 Apr 28.
Spermatogenesis is characterized by meiotic divisions and major morphological changes to produce spermatozoa that are capable of independent movement and fertilization of an egg. Male germ cell differentiation is governed by orchestrated, phase-specific gene expression patterns that are tightly cont
PMID 23632103

Human serum albumin and other proteins as templating agents for the synthesis of nanosized dopamine-eumelanin.

Chassepot A, Ball V.SourceUniversité de Strasbourg, Faculté de Chirurgie Dentaire, 1 place de l'Hôpital, 67000 Strasbourg, France.
Journal of colloid and interface science.J Colloid Interface Sci.2014 Jan 15;414:97-102. doi: 10.1016/j.jcis.2013.10.002. Epub 2013 Oct 12.
Eumelanin like materials are known to be heterogeneous and highly insoluble materials and hence it was difficult to use them for applications even if they display fascinating properties as photoprotection and photoconductivity. Owing to the known reactivity of quinones available on the surface of do
PMID 24231090

Dodecyl and octyl esters of fluorescein as protonophores and uncouplers of oxidative phosphorylation in mitochondria at submicromolar concentrations.

Shchepinova MM, Denisov SS, Kotova EA, Khailova LS, Knorre DA, Korshunova GA, Tashlitsky VN, Severin FF, Antonenko YN.SourceA.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia; Faculty of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia.
Biochimica et biophysica acta.Biochim Biophys Acta.2014 Jan;1837(1):149-58. doi: 10.1016/j.bbabio.2013.09.011. Epub 2013 Sep 27.
In our search for fluorescent uncouplers of oxidative phosphorylation, three esters of fluorescein, n-butyl-, n-octyl-, and n-dodecyl-oxycarbonyl-fluorescein (C4-FL, C8-FL, C12-FL) were synthesized and characterized. With increasing liposomal lipid content, the long-chain alkyl derivatives of fluore
PMID 24076107