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Topic: Parthenogenesis


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  Parthenogenesis - Wikipedia, the free encyclopedia
Parthenogenesis (Partheno-genesis from the Greek παρθενος, "virgin", + γενεσις, "birth") means the growth and development of an embryo or seed without fertilization by a male.
Parthenogenesis has nothing to do with artificial animal cloning, though the process is a form of natural cloning.
For example, the freshwater crustacean Daphnia reproduces by parthenogenesis in the spring to rapidly populate ponds, then switches to sexual reproduction as the intensity of competition and predation increases.
en.wikipedia.org /wiki/Parthenogenesis   (1331 words)

  
 Sex and sexuality (2)   (Site not responding. Last check: 2007-10-19)
In cases of parthenogenesis (virgin birth), an ovum starts to divide by itself without fertilization, producing an embryo in which the paternal chromosomes may be replaced by a duplication of maternal ones.
Artificial parthenogenesis has since been achieved in almost all major groups of animals, by mechanical, chemical, and electrical means, though it usually results in incomplete and abnormal development.
It is possible that some cases of human parthenogenesis involve self-fertilization rather than true virgin birth, as there are cases of sperm being produced in women by vestigial, usually nonfunctional, male reproductive glands known as the epoöphoron (parovarium) and paroöphoron, which correspond to the seminiferous tubules of the testicles in males.
ourworld.compuserve.com /homepages/dp5/sex2.htm   (3016 words)

  
 FILE: <BC-15
Parthenogenesis may be constant, occurring in each successive generation, or it may be cyclic in which case one or more parthenogenetic generations alternates with a bisexual.
Parthenogenesis may occur as a general condition throughout the range of the species, or it may be geographic in which case the parthenogenetic form occupies a different area from the bisexual.
Systematic and evolutionary implications of parthenogenesis in the Hymenoptera.
faculty.ucr.edu /~legneref/biotact/bc-15.htm   (1181 words)

  
 Researchers develop primate stem cells from unfertilized embryo
Parthenogenesis is defined as a process by which embryonic development is initiated directly from an unfertilized egg cell.
Parthenogenesis results in a microscopic ball of cells, called a blastocyst, typically 50 to 200 cells.
Vrana said, "Parthenogenesis offers an important new therapeutic strategy for a host of medical conditions." However, all of the researchers emphasized that human clinical applications will require years of further research and development.
www.eurekalert.org /pub_releases/2002-01/wfub-rdp012502.php   (436 words)

  
 ParthIndex.html   (Site not responding. Last check: 2007-10-19)
A third, less commonly observed form of parthenogenesis is embryonic tissue accompanied by dispersed aggregates of blood islets or an organized pattern resembling a 'blood ring'.
The phenomena of avian parthenogenesis is described as a process of cell division in an unfertilized egg that may result in the formation of embryonic tissues and in extreme situations a fully developed individual (Olsen,1975).
In most observations of avian parthenogenesis, the abortive expression of early embryonic development can be incorrectly identified as an early embryonic failure associated with the incubation process associated with fertilized eggs.
oregonstate.edu /Dept/animal-sciences/poultry   (593 words)

  
 Reproductive Biology Seminar   (Site not responding. Last check: 2007-10-19)
Parthenogenesis is a process, sometimes referred to as a virgin birth, in which an embryo is created solely from a female oocyte without any genetic contribution from a male (Beatty, 1957).
Even though the embryos from parthenogenesis could never be a viable fetus, there are still moral and ethical delimas to deal with when trying this technique in humans (Science News, 2002).
Scientists are presently experimenting with parthenogenesis in mammalian eggs, but the technique has only been applied in a limited capacity to human eggs.
uwadmnweb.uwyo.edu /inbre/PastPrograms/repro_Bamford.asp   (807 words)

  
 BBC News | SCI/TECH | Scientists use 'virgin birth' technique
Parthenogenesis has been observed in many lower animals, especially insects such as aphids.
Parthenogenesis has also been artificially induced in frogs and snakes, although it quite often results in abnormal development.
Because for females parthenogenesis would involve cell manipulation with no additional genetic material, it may prove to be a more ethically acceptable method of producing stem cells than the conventional transfer of nuclear DNA material from another person.
news.bbc.co.uk /1/hi/sci/tech/1676240.stm   (698 words)

  
 parthenogenesis
In many social insects, such as the honeybee and the ant, the unfertilized eggs give rise to the male drones and the fertilized eggs to the female workers and queens.
The phenomenon of parthenogenesis was discovered in the 18th cent.
Artificial parthenogenesis has since been achieved in almost all major groups of animals, although it usually results in incomplete and abnormal development.
www.factmonster.com /ce6/sci/A0837738.html   (289 words)

  
 D:\ASAWEB~1\PSCF\1983\JASA9-83Kessel.htm
Parthenogenesis is widely spread in the group and occurs in all three of the suborders.
Parthenogenesis is naturally occurring with polyploidy in three genera of frogs, viz., Ceratophrys, Hyla, and Odontophrynus.
Parthenogenesis is a very common phenomenon in the animal kingdom, forms with parthenogenetic reproduction being found in most animal groups.
www.asa3.org /ASA/PSCF/1983/JASA9-83Kessel.html   (5510 words)

  
 T'bone's SWU   (Site not responding. Last check: 2007-10-19)
Parthenogenesis, or "virgin birth," is the process whereby unfertilized females give birth to offspring.
Recently, three baby sharks were apparently born through parthenogenesis (see http://www.ananova.com/news/story/sm_674819.html?menu=news.scienceanddiscovery).
In Star Wars, from the very early drafts of the scripts, Lucas had included the prophecy of a chosen one that is formed from the substance of the spiritual essence of the universe itself, destined to embody the principles of the divine.
www.starwarz.com /tbone/guest_editorials/drdave_parthenogenesis.htm   (2331 words)

  
 American College of Surgeons 90th Annual Clinical Congress
Authors of the study believe parthenogenesis may be an alternative source of stem cells that does not require human embryonic tissue.
One advantage afforded by stem cells obtained through parthenogenesis is that they may be used in the same patient without immunosuppression (drug therapy to foster acceptance of foreign tissue).
Stem cells derived through parthenogenesis also could be used in other patients, in the same way as human embryonic stem cells, with immunosuppression, he added.
www.facs.org /clincon2004/pressinfo/pratala.html   (598 words)

  
 BBC News | SCI/TECH | Unfertilised monkey eggs give stem cells
Parthenogenesis is well documented in insects and lizards but is not normal in higher animals.
Researchers think that because parthenotes are incapable of developing into a foetus, their use may bypass some of the ethical objections that have dogged current experiments on normal embryos.
To suggest that such embryos were more acceptable because they could not develop into a foetus was "a 'technical fix' argument which would not satisfy a more holistic view, which would see this as no different in status from a non-viable cloned embryo or a non-viable IVF embryo".
news.bbc.co.uk /1/hi/sci/tech/1794661.stm   (766 words)

  
 ScienCentral Video News: Stem Cell Source
"Parthenogenesis is derived from the Greek terms 'parthenos' and 'genesis'," explains Kent Vrana, professor of physiology/pharmacology at Wake Forest University Baptist Medical Center.
So parthenogenesis is the process whereby an organism develops from an activated egg without the benefit of sperm.
Vrana emphasizes that parthenogenesis may be "one ethical alternative," in part because it can only be used to make therapeutic cells for women, who produce egg cells.
sciencentral.com /articles/view.php3?article_id=218392141&...   (826 words)

  
 Wired News:
In parthenogenesis, reproduction is achieved by development of an unfertilized egg.
Parthenogenesis offers one more possible route to obtaining stem cells, which many researchers believe could lead to cures for many ills -- from Alzheimer's to Parkinson's -- because the cells can become almost any kind of cell in the human body.
Jerry Hall, co-director of ViaGene Fertility, who uses parthenogenesis to get stem cells, was surprised that the government includes parthenotes (the products of parthenogenesis) in its definition of a human embryo.
www.wired.com /news/medtech/1,63203-1.html   (983 words)

  
 Changes In Development, Sperm Activity, and Parthenogenesis Across a 10^5 Exposure Range in Lytechinus ...
Egg activation without sperm contact, called parthenogenesis and artificial parthenogenesis, in sea urchin eggs has been investigated by many biologists since it was first studied by Oscar and Richard Hertwig during the 1880's.
Parthenogenesis in herbicide pollution proved to be a much smaller factor than in the insecticide, while sperm activity appeared to be moderately effected.
The notable difference between the number of eggs fertilized in the 1000 ppm concentrations of "Fertilization and Development" and "Parthenogenesis" supports the idea that these sperm were capable of suitable interaction with the egg to induce the formation of the fertilization membrane.
oas.ucok.edu /OJAS/97/T97/STINN.HTM   (3842 words)

  
 PathFactors.html   (Site not responding. Last check: 2007-10-19)
The overall incidence of parthenogenesis is higher in young hens (Olsen, 1967).
An increased occurance of parthenogenesis was observed in eggs from Beltsville Small Whitre turkey hens exposed to New Castle Disease, Fowl Pox (Olsen and Buss, 1967), and Rous Sarcoma viruses (Olsen and Poole, 1962).
A significant difference in parthenogenesis was observed between two lines of Medium White Turkey selected for divergent ejaculate volumes (Savage and Harper,1985).
oregonstate.edu /Dept/animal-sciences/poultry/ParthFactors.html   (327 words)

  
 Developmental Biology Online: The Invention of Artificial Parthenogenesis
Artificial parthenogenesis was an invention: "the artificial production of normal larvae (plutei) from the unfertilized eggs of the sea urchin."(2) Loeb found that by treating sea urchin eggs with appropriate inorganic salt solutions he could initiate embryological development, a process which up to that time had required the sperm of the male urchin.
Loeb discovered artificial parthenogenesis because he was seeking to control life on its most basic level; it was a natural consequence of his conviction that biology was and should be an engineering science concerned with transforming the natural order.
Artificial parthenogenesis in many respects set the images and the tone for the discussion of reproductive technology in the public mind for a long time to come; Loeb, on the cover of Harper's Weekly as one of a series of "Americans of To-Morrow," became the epitome of a new kind of biologist.
www.devbio.com /printer.php?ch=7&id=72   (6243 words)

  
 Parthenogenesis   (Site not responding. Last check: 2007-10-19)
Neither parthenogenesis nor triploidy has previously been reported in the infraorder Iguania, comprising the families Iguanidae, Agamidae, and Chamaeleontidae.
The probability of randomly collecting 33 females and no males from a bisexual population is about 1 in 1010, assuming an equal ratio and random distribution of the sexes.
One possible exception to the hybrid origin scheme is the parthenogenesis of certain Amazonian populations of Cnemidophoris lemniscatus, where there appears to be only one potential source species [16, 17].
bill-hall.afriherp.org /Content/Hall1970/Hall1970.htm   (1119 words)

  
 Asexual Reproduction
Parthenogenesis occurs in some fishes, several kinds of insects, and a few species of frogs and lizards.
Reproduction by parthenogenesis is more rapid that sexual reproduction, and the use of this mode of asexual reproduction permits the animals to quickly exploit the available resources.
Parthenogenesis is forced on some species of wasps when they become infected with bacteria (in the genus Wolbachia).
users.rcn.com /jkimball.ma.ultranet/BiologyPages/A/AsexualReproduction.html   (1565 words)

  
 Christdot :: Christ. Period. :: The implication of Parthenogenesis in the birth of Christ
The implication of Parthenogenesis in the birth of Christ
I was reading an article on an experiment that enabled a female mouse to reproduce without need of a father, based on Parthenogenesis.
Re: The implication of Parthenogenesis in the birth of Christ
christdot.org /modules.php?name=News&file=article&sid=3277   (865 words)

  
 New Scientist Breaking News - 'Virgin birth' method promises ethical stem cells   (Site not responding. Last check: 2007-10-19)
In parthenogenesis, an unfertilised egg keeps two sets of chromosomes and begins developing as if it had been fertilised.
And that, according to its proponents, is the beauty of the technique as far as stem cells are concerned: it produces embryos that could never become human beings.
However, because cells made by parthenogenesis have two identical sets of chromosomes, rather than one set each from the father and the mother, they have less variation in the surface proteins on cells that can trigger immune reactions.
www.newscientist.com /article.ns?id=dn3654   (597 words)

  
 THE VIRGIN BIRTH   (Site not responding. Last check: 2007-10-19)
Parthenogenesis is seen as a possible way to clone primates, with the emphasis on human cloning.
Parthenogenesis Parthenogenesis is a particular form of asexual reproduction in which females produce eggs that develop without fertilization.
Parthenogenesis was indeed a consistent supernatural belief regardless of subtext or societal environment.
www.reluctantatheist.com /VB.htm   (2760 words)

  
 Scientists Eye 'Virgin Birth' Phenomenon - CBS News
It's called parthenogenesis — Greek for "virgin birth." Now a few scientists are trying to take males out of the human equation as well, not to create babies but to develop stem cells for medical research.
Some researchers view parthenogenesis as a defense against complaints that their work is unethical.
Some supporters of this research, including Lanza, differ on this semantic point, saying the creations are clearly "embryos." And because these creations are destroyed in the process of harvesting the stem cells, opponents say this method too is akin to taking human life.
www.cbsnews.com /stories/2003/05/05/tech/main552408.shtml   (967 words)

  
 Parthenogenesis   (Site not responding. Last check: 2007-10-19)
Parthenogenesis is inspired by natural occurrences in select species.
Based on this phenomena, scientists have been able to study and better understand parthenogenesis so that it may be recreated artificially through experiments on the cellular level.
This replication has raised scientific and societal issues regarding the use of parthenogenesis in typically non-parthenogenetic species.
www.brown.edu /Courses/BI0032/partheno/Parthenogenesis.htm   (85 words)

  
 Evolution trend in parthenogenesis reproductive strategies   (Site not responding. Last check: 2007-10-19)
Since parthenogenesis is common in plants, moderately common in invertebrate animals, occasionally reported in fish, frogs and lizards, but never reported in birds and mammals.
I actually did a search on PubMed and there are numerous papers stating the occurence of parthenogenesis in turkeys.
Parthenogenesis might favor species which have more offspring than which survive(r specialists).
www.biology-online.org /biology-forum/about1003.html   (514 words)

  
 Parthenogenesis - Virgin Birth - Gynogenesis
Parthenogenesis or "virgin birth" is the asexual reproductive process by which a female's egg undergoes embryonic development without the fertilizing union of a male's sperm.
Parthenogenesis - Virgin Birth - Genetics - Gynogenesis.
parthenogenesis, gynogenesis, virgin birth, genetics, parthenogenetic reproduction, gynogenetic development parthenogenesis, gynogenesis, virgin birth, genetics We are wondrous and powerful magnets, therefore our magnetic power hinges upon our use of thought.
www.braincourse.com /virga.html   (510 words)

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