Editing Embryo transfer (section)

=== Frozen embryo transfer in animals ===
[[File:Embriões Bovinos.jpg|thumb|Bovine embryos ''in vitro.'']]
The development of various methods of [[cryopreservation]] of [[bovine]] [[embryos]]<ref>{{cite journal |vauthors=Wilmut I, Rowson LE |year=1973 |title=Experiments on the low-temperature preservation of cow embryos |journal=Vet Rec |volume=92 |issue=26 |pages=686–690 |doi=10.1136/vr.92.26.686 |pmid=4730118 |title-link= embryos |doi-broken-date=1 November 2024 |s2cid=46005842 }}</ref><ref>Leibo SP, Mazur P. 1978. Methods for the preservation of mammalian embryos by [[freezing]]. In: Mapletoft. History and [[bovine]] [[embryo]] transfer. Anim. Reprod., v.10, n.3, p.168-173, Jul./Sept. 2013 173</ref> improved embryo transfer technique considerably efficient technology, no longer depending on the immediate readiness of suitable recipients. Pregnancy rates are just slightly less than those achieved with fresh embryos.<ref>Leibo SP, Mapletoft RJ. 1998. Direct transfer of cryopreserved [[cattle]] [[embryos]] in North America. In: Proceedings of the 17th Annual Convention of [[AETA]], 1998, San Antonio, TX. San Antonio, TX: AETA. pp. 91-98.</ref> Recently, the use of [[cryoprotectants]] such as [[ethylene glycol]] has permitted the direct transfer of bovine embryos.<ref>{{cite journal | vauthors = Voelkel SA, Hu YX | year = 1992 | title = Direct transfer of frozen-thawed bovine embryos | journal = Theriogenology | volume = 37 | issue = 3| pages = 23–37 | doi=10.1016/0093-691x(92)90245-m| pmid = 16727070 }}</ref><ref>{{cite journal | vauthors = Hasler JF, Hurtgen PG, Jin ZQ, Stokes JE | year = 1997 | title = Survival of IVF-derived bovine embryos frozen in glycerol or ethylene glycol | journal = Theriogenology | volume = 48 | issue = 4| pages = 563–579 | doi=10.1016/s0093-691x(97)00274-4| pmid = 16728153 }}</ref> The world's first live [[crossbred]] bovine calf produced under [[tropical]] conditions by Direct Transfer (DT) of embryo [[freezing|frozen]] in ethylene glycol freeze media was born on 23 June 1996. Dr. Binoy Sebastian Vettical of Kerala Livestock Development Board Ltd has produced the embryo stored frozen in Ethylene Glycol freeze media by [[slow programmable freezing]] (SPF) technique and transferred directly to recipient [[cattle]] immediately after thawing the frozen straw in water for the birth of this calf. In a study, in vivo produced crossbred bovine embryos stored frozen in ethylene glycol freeze media were transferred directly to recipients under tropical conditions and achieved a pregnancy rate of 50 percent.<ref>Binoy Sebastian Vettical, Kuruvilla Varghese and K.Muraleedharan. [[Cryopreservation]] of [[Embryos]] in [[Ethylene Glycol]] Freeze Media and Direct Transfer in [[Crossbred]] [[Cattle]] in the [[Tropics]], Compendium: 9th International Congress on [[Biotechnology]] in Animal Reproduction</ref> In a survey of the North American embryo transfer industry, embryo transfer success rates from direct transfer of embryos were as good as to those achieved with [[glycerol]].<ref>Leibo SP, Mapletoft RJ. 1998. Direct transfer of [[cryopreserved]] [[cattle]] [[embryos]] in North America. In: Proceedings of the 17th Annual Convention of [[AETA]], 1998, San Antonio, TX. San Antonio, TX: [[AETA]]. pp. 91-98.</ref> Moreover, in 2011, more than 95% of frozen-thawed embryos were transferred by Direct Transfer.<ref>{{cite journal | vauthors = Stroud B | year = 2012 | title = The year 2011 worldwide statistics of embryo transfer in domestic farm animals. | journal = IETS Newslet | volume = 50 | pages = 16–25 }}</ref>