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In the strictest sense immunocontraception is the use of an animal's immune system to prevent it from fertilizing offspring. More generally the field of immunocontraception includes related technologies that prevent embryonic implantation. Typically immunocontraception involves the administration of a vaccine that induces an adaptive immune response which causes an animal to become temporarily infertile. Contraceptive vaccines have been used in numerous settings for the control of wildlife populations. However, experts in the field believe that major innovations are required before immunocontraception can become a practical form of contraception for human beings. Thus far immunocontraception has focused on mammals exclusively. There are several targets in mammalian sexual reproduction for immune inhibition. They can be organized into three categories. ;Gamete production: Organisms that undergo sexual reproduction must first produce gametes, cells which have half the typical number of chromosomes of the species. Often immunity that prevents gamete production also inhibits secondary sexual characteristics and so has effects similar to castration.〔(【引用サイトリンク】url=http://www.amplicon-vaccine.com/technology.html )〕〔(【引用サイトリンク】url=http://www.improvac.co.nz/sites/improvac/en-nz/Pages/betterwayforward.aspx )〕 ;Gamete function: After gametes are produced in sexual reproduction, two gametes must combine during fertilization to form a zygote, which again has the full typical number of chromosomes of the species. Methods that target gamete function prevent this fertilization from occurring and are true contraceptives. ;Gamete outcome: Shortly after fertilization a zygote develops into a multicellular embryo that in turn develops into a larger organism. In placental mammals this process of gestation occurs inside the reproductive system of the mother of the embryo. Immunity that targets gamete outcome induces abortion of an embryo while it is within its mother's reproductive system. ==Medical use== Immunocontraception promises many advantages over methods of contraception currently available for human use. It does not require surgical intervention, unlike procedures such as vasectomy or tubal ligation. It does not require action by participants concomitant with the act of intercourse, unlike methods such as the use of condoms. The form of contraception most comparable to prospective immunocontraceptive products for humans is hormonal contraception, over which immunocontraception offers several advantages: it can be effective with as infrequent as annual dosing, rather than a daily pill regimen;〔 it can be used by both males and females, rather than just females;〔 it does not entail the side effects of ingesting synthetic hormones, where undesired side effects exist. Furthermore, the demand for contraception is greatest in parts of the developing world, where population growth is greatest, but this is also where access to hormonal contraceptives is least. While access to daily pharmaceuticals may be generally poor in less-developed countries, most countries have an infrastructure for mass immunization.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「immunocontraception」の詳細全文を読む スポンサード リンク
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