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Encyclopedia > Oogenesis

Oogenesis or rarely oögenesis is the creation of an ovum (egg cell). It is the female process of gametogenesis. It involves the various stages of immature ova. A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Gametogenesis is the creation of gametes by meiotic division of gametocytes into various gametes. ...

Contents

Oogenesis in mammals

In mammals, oogenesis occurs in the ovarian follicle of the ovary. Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ... Ovarian follicles or Graafian follicles (after Regnier de Graaf) are the roughly spherical cell aggregations in the ovary containing an ovum and from which the egg is released during ovulation. ... // For ovary as part of plants see ovary (plants) An ovary is an egg-producing reproductive organ found in female organisms. ...


It is interesting to note that such an important process in animal life cycles is done completely without the aid of spindle-coordinating centrosomes. The mitotic spindle is a structure of the eukaryotic cytoskeleton involved in mitosis and meiosis. ... The centrosome is the main microtubule organizing center (MTOC) of the cell as well as a regulator of cell-cycle progression. ...


It consists of several processes: oocytogenesis, ootidogenesis and the final maturity to form an ovum. Folliculogenesis is a separate process during ootidogenesis. In biology, folliculogenesis refers to the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte. ...

Cell type ploidy Process Process completion
Oogonium diploid Oocytogenesis (mitosis) third trimester (forming oocytes)
primary Oocyte diploid Ootidogenesis (meiosis 1) (Folliculogenesis) Dictyate in prophase I until ovulation
secondary Oocyte haploid Ootidogenesis (meiosis 2) Halted in metaphase II until fertilization
Ootid haploid  ? Minutes after fertilization
Ovum haploid

Ploidy is the number of homologous sets of chromosomes in a biological cell. ... An oogonium is a female gametogonium. ... Mitosis divides genetic information during cell division. ... The human gestation period of approximately 40 weeks between the time of the last menstrual cycle and delivery is traditionally divided into three periods of three months, or trimesters. ... An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ... For the figure of speech, see meiosis (figure of speech). ... In biology, folliculogenesis refers to the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte. ... The Dictyate stage of meiotic prophase is the prolonged resting phase that is terminated shortly before ovulation. ... An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ... For the figure of speech, see meiosis (figure of speech). ... An ootid is a female gametid, as opposed to a male spermatid. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ...

Creation of oogonia

The creation of oogonia traditionally doesn't belong to oogenesis, but to the common path of gametogenesis together with spermatogenesis. Gametogenesis is the creation of gametes by meiotic division of gametocytes into various gametes. ...


Oocytogenesis

Oogenesis starts with oogonial transformation into primary oocytes, called oocytogenesis[1]. Oocytogenesis is completed either before or shortly after birth. An oogonium is a female gametogonium. ... An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ...


Number of primary oocytes

It is commonly said that when oocytogenesis is completed, no additional primary oocytes are created, in contrast to the male spermatogenesis, where gametocytes are continuously created. In other words, oocytes reaches their maximum at ~20[2][3] Renewal of ovarian follicles from germline stem cells (originating from bone marrow and peripheral blood) was reported in the postnatal mouse ovary. Due to the revolutionary nature of these claims, further experiments are required to examine the dynamics of small follicle formation.


Ootidogenesis

The succeeding ootidogenesis is the step in which the primary oocyte turns into an ootid. It is achieved by meiosis. The primary oocyte is even defined from its role to undergo meiosis[4]. An oocyte, ovocyte, or rarely oöcyte is a female gametocyte or germ cell involved in reproduction. ... For the figure of speech, see meiosis (figure of speech). ...


However, although this process begins at prenatal age, it stops at prophase I. In late fetal life, all oocytes, still primary oocytes, have taken this halt in development, called dictyate. First after menarche they continue to develop, although only a few does so every menstrual cycle. The Dictyate stage of meiotic prophase is the prolonged resting phase that is terminated shortly before ovulation. ...


Meiosis I

Meiosis I of ootidogenesis starts at embryonic age, but halts in diplotene of prophase I until puberty. For those primary oocytes continuing to develop in each menstrual cycle, however, synapsis occurs and tetrads form, enabling and crossing over. As a result of meiosis I, the primary oocyte becomes the secondary oocyte and the first polar body. In biology, meiosis is the process that allows one diploid cell to divide in a special way to generate haploid cells in eukaryotes. ... This page covers notations and definitions, sometimes called the Cartan formalism, for the Cartan connection concept. ... Thomas Hunt Morgans illustration of crossing over (1916) Homologous Recombination is the process by which two chromosomes, paired up during prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but... Polar body is a cell structure found inside an ovum. ...


Meiosis II

Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II. However, this, too is halted in metaphase II. However, this only lasts until fertilization, if such occurs. When meiosis II is completed, an ootid and another polar body is created. Categories: Biology stubs ...


Folliculogenesis

Main article: Folliculogenesis

Synchronously as ootidogenesis, the ovarian follicle surrounding it develops from a primordial follicle to a preovulatory one. In biology, folliculogenesis refers to the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte. ... Ovarian follicles or Graafian follicles (after Regnier de Graaf) are the roughly spherical cell aggregations in the ovary containing an ovum and from which the egg is released during ovulation. ...


Maturation into ovum

Both polar bodies at the end of Meiosis II disintegrate leaving only the ootid which undergoes maturation and eventually matures into an ovum.


Oogenesis in non-mammals

Many protists produce egg cells in structures termed archegonia. Some algae and the oomycetes produce eggs in oogonia. In the brown alga Fucus, all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity. Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ... For the programming language, see algae (programming language). ... Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ... A cell that arises from a primordial germ cell and differentiates into an oocyte in the ovary. ... Species F. serratus F. vesiculosus Fucus is a genus of seaweed that lives in the intertidal zones of rocky shores. ...


In plants, oogenesis occurs inside the female gametophyte via mitosis. In many plants such as bryophytes, ferns, and gymnosperms, egg cells are formed in archegonia. In flowering plants, the female gametophyte has been reduced to an eight-celled embryo sac within the ovule inside the ovary of the flower. Oogenesis occurs within the embryo sac and leads to the formation of a single egg cell per ovule. For other uses, see Plant (disambiguation). ... In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... Mitosis divides genetic information during cell division. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... This article is about the group of pteridophyte plants. ... Divisions Pinophyta (or Coniferophyta) - Conifers Ginkgophyta - Ginkgo Cycadophyta - Cycads Gnetophyta - Gnetum, Ephedra, Welwitschia Gymnosperm (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, which are usually arranged in cone-like structures. ... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... Location of ovules inside a Helleborus foetidus flower Ovule literally means small egg. ... This article or section does not adequately cite its references or sources. ... Longitudinal section of female flower of squash showing ovary, ovules, pistil, and petals In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. ...


In ascaris, the oocyte does not even begin meiosis until the sperm touches it, in contrast to mammals, where meiosis is completed in the menstrual cycle. Species Ascaris lumbricoides Ascaris suum Ascaris is a genus of parasitic nematodes. ... For other uses, see Sperm (disambiguation). ...


See also

An oogonium is a female gametogonium. ... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ... An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ...

References

  1. ^ NCBI - The saga of the germ line
  2. ^ [http://humrep.oxfordjournals.org/cgi/content/full/18/9/1762 Early ovarian ageing: a hypothesis What is early ovarian ageing? pmid = 16051153}}
  3. ^ Johnson J, Canning J, Kaneko T, Pru J, Tilly J (2004). "Germline stem cells and follicular renewal in the postnatal mammalian ovary.". Nature 428 (6979): 145-50. doi:10.1038/nature02316. PMID 15014492. 
  4. ^ Biochem

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

  • http://distance.stcc.edu/AandP/AP/AP2pages/reprod/oogenesi.htm
  • Reproductive Physiology
The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ... The Bartholins glands (also called Bartholin glands or greater vestibular glands) are two glands located slightly below and to the left and right of the opening of the vagina in women. ... Bartholins ducts are a pair of ducts leading from the Bartholins glands to the surface of the vulva. ... In human anatomy, the Skenes glands (also known as the lesser vestibular, periurethral glands, or paraurethral glands[1]) are glands located on the upper wall of the vagina, around the lower end of the urethra. ... The Skenes ducts are a pair of ducts leading from the Skenes glands to the surface of the vulva, to the left and right of the urethral opening. ... Between the hymen and the frenulum of the labia is the fossa of vestibule of vagina (or fossa navicularis), while in the groove between the hymen and the labium minus, on either side, the small opening of the greater vestibular gland (Bartholin’s) can be seen. ... The fornices of the vagina are the deepest portions of the vagina, extending into the recesses created by the extension of the cervix into the vaginal space. ... For the Greek god of marriage, see Hymenaios. ... The vaginal orifice is a median slit below and behind the opening of the urethra; its size varies inversely with that of the hymen. ... The Wolffian duct (also known as archinephric duct, Leydigs duct, mesonephric duct, or nephric duct) is a paired organ found in mammals including humans during embryogenesis. ... Gartners duct is a potential embryological remnant in human female development of the mesonephric ducts. ... The epoophoron , also called organ of Rosenmüller, is a remnant of the Wolffian duct that can be found next to the ovary and fallopian tube. ... The paroöphoron consists of a few scattered rudimentary tubules, best seen in the child, situated in the broad ligament between the epoöphoron and the uterus. ... The Canal of Nuck, described by Anton Nuck in 1691, is an abnormal patent pouch of peritoneum extending into the labium major of women. ... ... Female internal reproductive anatomy The urethral sponge is a spongy cushion of tissue, found in the lower genital area of women, that sits against both the pubic bone and vaginal wall, and surrounds the urethra. ...

  Results from FactBites:
 
Oogenesis - Wikipedia, the free encyclopedia (154 words)
Oogenesis is the creation of an ovum (egg cell) in the ovarian follicle of the ovary.
Oogenesis is not to be confused with oocytogenesis, which is the formation of oocytes, which are the female gametocytes that divide later into ova.
In mammals, oogonial transformation into oocytes (oocytogenesis) is completed either before or shortly after birth.
  More results at FactBites »

 
 

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