Infobox Anatomy Name Oogonium Latin GraySubject 3 GrayPage 38 Image Caption Image2 Caption2 System MeshName Oogonia MeshNumber A05.360.490.690.700 Oogonium plural oogonia may refer to either a primordial oocyte in a female fetus or the female gametangium of certain thallophyte s. In the Mammalian Fetus Main Oogenesis Oogonia are formed in large numbers by mitosis early in fetus fetal development from germ cell primordial germ cell s. In humans they start to develop between weeks 4 and 8 and are present in the fetus between weeks 5 and 30. Structure Normal oogonia in human ovary ovaries are round or ovoid in shape and are found amongst neighboring somatic cells and oocytes at different phases of development. Oogonia can be distinguished from neighboring somatic cells, under an electron microscope , by observing their nucleus nuclei . Oogonial nuclei contain randomly dispersed fibrillar and granular material whereas the somatic cells have a more condensed nucleus that creates a darker outline under the microscope. Oogonial nuclei also contain dense prominent nucleoli . The chromosome chromosomal material in the nucleus of mitotically dividing oogonia shows as a dense mass surrounded by vesicles or double membranes. ref name structure cite journal last Baker first T.G. coauthors L. L. Franchi title The Fine Structures of Oogonia Oocytes in Human Ovaries journal Journal of Cell Science year 1967 volume 2 pages 213 224 pmid 4933750 url http jcs.biologists.org content 2 2 213.full.pdf ... in which one oogonium divides unequally to produce one daughter cell that will eventually become an oocyte through the process of oogenesis , and one daughter cell that is an identical oogonium to the parent ... is required for the germ cell to differentiation into an oogonium and eventually enter meiosis. One .... ref name njmd In Thallophytes In phycology and mycology , oogonium refers to a female gametangium ... io Oogonio id Oogonium kk ja pl L gnia ru ... more details
Unreferenced date December 2006 A gametogonium plural gametogonia is a germ cell that divides into gametocyte s during gametogenesis . Male gametogonia are called spermatogonium spermatogonia , and female gametogonia are called oogonium oogonia . Category Germ cells Cell biology stub th ... more details
A gonocyte is a long lived germ cell responsible for gametogenesis , which is spermatogenesis in males, and oogenesis in females. Gonocytes include gametogonium gametogonia Spermatogonium spermatogonia and Oogonium oogonia , oocyte s, ootid s, and Ovum ova . The term often also refers to the primordial germ cells . It often does not include the short lived spermatocyte , spermatid , or sperm cells. Fact date April 2008 Reproductive physiology Category Developmental biology Category Reproductive system Category Germ cells cell biology stub pl Gonocyt ... more details
Unreferenced date May 2007 Image Hyaloperonospora parasitica hyphae oospore 2.jpg thumb right 300px Oospores of Hyaloperonospora parasitica , agent of the downy mildew in the middle An oospore is a thick walled sexual spore that develops from a fertilized oosphere union of oogonium and antheridium in some algae and fungi . Also the result of plasmogamy karyogamy in oomycetes, which in turn leads to the development of hyphae, then mycelium. Category Reproduction biology stub cs Oosf ra de Oospore es Oospora fr Oospore io Oosporo nl O spore pl Oospora pt O sporo ... more details
cleanup date October 2010 Infobox Anatomy Name Immature ovum Latin GraySubject GrayPage Image Caption Image2 Caption2 System MeshName MeshNumber An immature ovum is a cell that goes through the process of oogenesis to become an ovum . It can be an oogonium , an oocyte or an ootid . An oocyte, in turn, can be either primary or secondary, depending on how far it has come in its process of meiosis . class wikitable Cell type ploidy chromosomes chromatids Process Process completion Oogonium diploid 46 2N Oocytogenesis mitosis third trimester primary Oocyte diploid 46 4N Ootidogenesis meiosis 1 Folliculogenesis polar body separated Dictyate in prophase I until ovulation secondary Oocyte haploid 23 2N Ootidogenesis meiosis 2 polar body separated Halted in metaphase II until fertilization Ootid haploid 23 1N Maturation Minutes after fertilization Ovum haploid 23 1N Oogonium Main Oogonium Oogonia are the cells that turn into primary oocytes in oogenesis. ref http www.answers.com topic oogonium?cat health answers.com ref They are diploid, i.e. containing both pairs of homologous chromosomes. There are 23 chromosome pairs. Thus there are 46 chromosomes. Each chromosome, however, hasn t yet duplicated itself. Thus, there are only one chromatid on each chromosome, making the total quantity of chromatids 46. This is twice the number of chromosome pairs 2N . Timeline Oogonia are created in early embryo nic life. All have turned into primary oocytes at late fetal age. Primary oocyte Main Oocyte The primary oocyte is defined by its process of ootidogenesis , which is meiosis. ref http www.biochem.northwestern.edu holmgren Glossary Definitions Def P primary oocyte.html Biochem ref It has duplicated its DNA, so that each chromosome has two chromatids, i.e. 92 chromatids all in all 4C . When meiosis I is completed, one secondary oocyte and one polar body is created. Timeline Primary oocytes have been created in late fetal life. This is the stage where immature ova spend most of their ... more details
italic title Refimprove type protist date December 2009 Taxobox color lightgreen name Oedogonium regnum Protista divisio Chlorophyta classis Chlorophyceae ordo Oedogoniales genus Oedogonium genus authority Karl Engelbrecht Hirn Hirn , 1900 Link ref name algaebase Oedogonium is a genus of filamentous green algae . Filamentous means the colony is one cell thick. Reproduces in two ways sexually and asexually. Reproduces sexually through syngamy . The anthridia which produces sperm and the oogonium which produces the egg, release the sperm and egg. The egg and sperm then fuse and form a zygote 2n . The zygote then produces the filamentous green algae which is haploid 1n . The oedogonium can also produce asexually through zoospores. These separate from the parent plant through the zoosporangium and continue to divide producing the filamentous green algae. Oedogium is usually freefloating when mature though it can be attached to plants. Lives in quiet, fresh water. It has a spirally shape with a greenish tinge to it DISTRIBUTION OF SEX ORGAN species of oedogonium are divided into the following two groups on the basis of distribution of sex organ A MACRANDOUS SPECIES In these species antheridia are borne on the filament of normal size. where antheridia and oogonia are found on the same filament, are called MACRANDOUS MONOECIOUS. and where anthredia and oogonia are borne on the different filament, are known as MACRANDOUS DIOECIOUS. Although filament bearing anthredia and oogonia are morphologically similar, they differ physiologically. B NANNANDROUS SPECIES In nannandrous species filament bearing anthredia and oogonia show morphilogical distinction. the male filament, which are much smaller than the female filament, are called dwarf male or nannandrium. nannandrous species are always dioecious, i.e., anthridia and oogonia are borne on different filaments. References Reflist refs ref name algaebase AlgaeBase genus name Oedogonium id 43424 ref Category Chlorophyceae Chlorophy ... more details
Unreferenced stub auto yes date December 2009 A gametangium plural gametangia is an Organ anatomy organ or cell biology cell in which gamete s are produced that is found in many multicellular protist s, algae , Fungus fungi , and the gametophyte s of plant s. In contrast to gametogenesis in animal s, a gametangium is a haploid structure and formation of gametes does not involve meiosis . Types of gametangia Depending on the type of gamete produced in a gametangium, several types can be distinguished. Female Main Archegonium Oogonium Female gametangia are most commonly called Archegonium archegonia . They produce egg cell s and are the sites for fertilization . Archegonia are common in algae and primitive plants as well as gymnosperm s. In flowering plant s, they are replaced by the embryo sac inside the ovule . Male Main Antheridium The male gametangia are most commonly called Antheridium antheridia . They produce Sperm sperm cells that they release for fertilization. Antheridia producing non motile sperm spermatia are called spermatangia . Some antheridia do not release their sperm. For example, the oomycete antheridium is a syncytium with many sperm Cell nucleus nuclei and fertilization occurs via fertilization tubes growing from the antheridium and making contact with the egg cells. Antheridia are common in the gametophytes in lower plants such as bryophyte s, fern s, cycad s and ginkgo . In higher plants such as conifer s and flowering plants, they are replaced by pollen grain s. Isogamous In isogamy , the gametes look alike and cannot be classified into male or female. For example, in zygomycete s, two gametangia single cells at the end of hypha e form upon contact with each other and fuse into a zygospore . Category Reproduction Category Reproductive system Category Germ cells Botany stub cs Gametangium da Gametangium de Gametangium fr Gam tange kk lv Gametangiji nl Gametangium pl Gametangium pt Gamet ngio ru uk ... more details
italic title Taxobox name Sphaerotheca castagnei image image caption regnum Fungus Fungi divisio Ascomycota classis Leotiomycetes ordo Erysiphales familia Erysiphaceae genus Sphaerotheca fungus Sphaerotheca species S. castagnei binomial Sphaerotheca castagnei binomial authority Joseph Henri L veill L v. Sphaerotheca castagnei is a species of ascomycete fungi in the Erysiphaceae family. A plant pathogen , it causes a form of Powdery mildew . Description The mycelium is abundant and persistent or sometimes inconspicuous, occurring on either side or both sides of the infected leaves. The perithecia are abundant, scattered or somewhat aggregated, small, usually about 75 micrometre m long, but varying from 60&ndash 100 m. The texture is soft, surface uneven, reticulations very large and irregular, 20&ndash 30 m. The appendages are long, stout, usually colored throughout, but sometimes colorless, flexuous, somewhat uneven in width, and more or less interwoven with the mycelium. The ascus is rather small, elliptical or suborbicular in shape. ref cite book title North American Pyrenomycetes last Ellis JB, Everhart JM. year 1892 publisher Newfield location New Jersey pages 8&ndash 9 ref Development of the perithecium The oogonium and antheridium , which are formed where two neighboring hypha e approach, each contain a single nucleus cell nucleus . The cell wall between these organs is dissolved at the time of fertilization and the male and female nuclei unite and a fresh wall is laid down between the two organs. File Perithecium no text.PNG thumb left Perithecium with 8 pairs of ascospores green in each ascus Now the wall of the future perithecium beings to form by the development of a number of upright hyphal branches around the oogonium, forming a pseudo parenchymatous tissue, while the other branches later absorbed grow into the interior of the developing perithecium, while the outer cell walls become flattened and darker in color. Like other species in ... more details
oogonium oogonia , which occurs via the transformation of Ovarian follicle primordial follicles ... is completed in the estrus cycle. See also Oogonium Archegonium Oocyte Spermatogenesis References ... more details
Taxobox image width 250px image Fucus serratus2.jpg regnum Chromalveolata divisio Heterokont ophyta classis Brown algae Phaeophyceae ordo Fucales familia Fucaceae genus Fucus species F. serratus binomial Fucus serratus binomial authority Carl Linnaeus L. NOTOC Fucus serratus is a seaweed of the north Atlantic Ocean , known as toothed wrack or serrated wrack . ref cite book isbn 0 86033 046 X title The book of seaweed author Alan P. Major year 1977 publisher Gordon Cremonesi ref It is olive brown in colour and similar to bladder wrack F. vesiculosus and Fucus spiralis . It grows from a discoid holdfast . The fronds are flat, about 2 cm wide, bifurcating, and up to 1 m long including a short Stipe botany stipe . It branches irregularly dichotomously. The flattened blade has a distinct midrib and is readily distinguished from related taxa by the serrated edge of the fronds. It does not have air vesicle biology vesicle s, such as are found in F. vesiculosus , nor is it spirally twisted like F. spiralis . The reproductive bodies form in conceptacles sunken in Receptacle botany receptacles towards the tips on the branches. In these conceptacles Oogonium oogonia and antheridia are produced and after meiosis the oogonia and anteridia are released. Fertilisation follows and the zygote develops, settles and grows directly into the diploid sporophyte plant. Distribution and ecology Fucus serratus is found along the Atlantic coast of Europe from Svalbard to Portugal , in the Canary Islands and on the shores of north east Americas America . ref name Taylor 72 Cite book author W. R. Taylor year 1972 title Marine Algae of the Northeastern Coast of North America publisher University of Michigan Press isbn 0 472 08840 8 page 520 pp ref ref cite web url http www.algaebase.org search species detail ?species id 85&sk 0&from results title Fucus serratus Linnaeus work AlgaeBase author M. D. Guiry & Wendy Guiry date 2006 11 23 ref It was introduced to Iceland and the F ... more details
as A1 and A2. When mated, Antheridium antheridia introduce gametes into Oogonium oogonia , either by the oogonium ... lower half of the oogonium paragyny , and the union producing oospores. Like animals, but not like ... more details
Infobox Anatomy Name Oocyte Latin GraySubject 3 GrayPage 38 Image Oocyte.jpg Caption Stripped human oocyte granulosa cells that had surrounded this oocyte have been removed. Image2 Caption2 System MeshName Oocytes MeshNumber A05.360.490.690.680 An oocyte , ovocyte , or rarely ocyte , is a female gametocyte or germ cell involved in biological reproduction reproduction . In other words, it is an immature ovum , or ovum egg cell. An oocyte is produced in the ovary during female gametogenesis . The female germ cells produce a primordial germ cell PGC which undergoes meiosis to form an oogonium. During oogenesis the oogonium becomes a primary oocyte pronounced oh a site . Formation File Gray5.svg thumb 260px Diagram showing the reduction in number of the chromosomes in the process of maturation of the ovum . Main Oogenesis The formation of an oocyte is called oocytogenesis, which is a part of oogenesis. ref http www.answers.com topic oogenesis?cat health answers.com ref Oogenesis results in the formation of both primary oocytes before birth, and of secondary oocytes after it as part of ovulation . class wikitable Cell type ploidy chromosomes chromatids Process Time of completion Oogonium diploid 46 2N Oocytogenesis mitosis third trimester primary Oocyte diploid 46 2N Ootidogenesis meiosis 1 Folliculogenesis Dictyate in prophase I until ovulation secondary Oocyte haploid 23 1N Ootidogenesis meiosis 2 Halted in metaphase II until fertilization Ootid haploid 23 1N Ootidogenesis meiosis 3 Minutes after fertilization Ovum haploid 23 1N Characteristics File Oocyte granulosa cells.jpg thumb Human oocyte with surrounding granulosa cells Cytoplasm Oocytes are rich in cytoplasm which contains yolk granules to nourish the cell early in development. Nucleus During the primary oocyte stage of oogenesis, the nucleus is called a germinal vesicle. ref http www.biology online.org dictionary Germinal vesicle Biology online ref The only normal human type of secondary oocyte has the 23rd se ... more details
and Oogonium oogonia . ref name Hughes Because Aphanomyces euteiches is homothallic the antheridium and oogonium arise from the same hypha and are Self incompatibility self compatible , meaning separate ... an oogonium, which then develops into a single oospore, ref name Agrios Agrios, George N. 2005. Plant ... more details
a male and a female type gametangia called an antheridium male and an oogonium female . The antheridium ... or develop into the female gametangia which is an oogonium. Karyogamy between these two ... more details
develop male and female Gametangium gametangia called, respectively, Antheridium antheridia and Oogonium oogonia ref name Hughes . The antheridium fertilizes an oogonium, which then develops into a single ... more details
Encyclopedia
top
