Embryo transfer

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The embryo transfer (also embryo transfer ) is a technique in which embryos of mammals artificially into a uterus be introduced. In animal breeding, the embryos can come from other, often artificially fertilized females or, in humans and animals, from in vitro fertilization , an artificial insemination in a test tube.

8-cell embryo for implantation in the uterus three days after fertilization

term

Embryo transfer is made up of the Greek émbryon (seedling in the initial stage of development) and the Latin transferre (transplant, transfer).

Areas of application

Animal breeding

Embryo transfer has been used successfully in animal breeding since the 1970s in order to obtain as many offspring as possible from high-performing animals, for example cows with high milk yield, without having to go the “detour” via male offspring with uncertain characteristics. In order to protect the "super animals" or to use several cycle phases for egg cell production, the embryos are used by other female animals, the foster parents. In Germany in 1974 the insemination station Neustadt an der Aisch successfully obtained embryos from dairy cows and transferred them to other animals.

In the short term, embryo transfer promises great success, as already successful gene combinations can be fairly safely spread. The embryo transfer working group of German-speaking countries is the union of the relevant scientists and breeders.

Genetic engineering

Embryo transfer is also used in genetic engineering to obtain whole animals from cloned or transgenic egg cells.

Artificial fertilization

We also speak of embryo transfer in humans when the embryos created by artificial insemination are introduced into a woman's hormonally prepared uterus.

Procedure

Sperm are obtained from a male for artificial insemination . The mother animal, a female with the desired characteristics, is brought to multiple ovulation - superovulation - through hormone administration . These egg cells are either artificially fertilized in the mother animal or taken from the mother animal and artificially fertilized in the test tube, where they grow into embryos. The egg cells fertilized in the mother also grow into small embryos and are flushed out of the uterus.

The embryos obtained are transplanted into (often hormonally prepared) surrogate mothers or foster animals, where they grow into complete animals.

Procedure in humans

In in vitro fertilization , too, the embryos of the mother fertilized outside the body (“in the retort”) are artificially inserted. They are flushed into the uterus through a thin tube . This happens at a very early stage (72 hours after fertilization; the embryos at this point consist of two or four cells ). According to the current legal situation, never more than three human embryos can be transferred at the same time in order to keep the number of multiple pregnancies low. The trade in human embryos is prohibited under the Embryo Protection Act.

Procedure in cattle

In animal breeding, efforts are made to obtain more calves from particularly productive cows . In the donor animal (e.g. a high-performance dairy cow with> 11,000 liters annual output) hormone treatment causes several egg cells (usually 20–30) to ripen at the same time . Seven days after fertilization , the embryos are rinsed out and carrier animals are placed in the uterus. Frozen to −196 ° C, embryos of varying quality can be purchased by every farmer for his / her breeding.

Procedure with the mouse

For the embryo transfer, pseudopregnant females are required. This is obtained by mating sexually intact females with sterile, vasectomized males. By copulating with vasectomized males is in rodents females , a hormone produced corresponding to a pregnant animal even if no fertilized eggs in the reproductive tract are. The pseudopregnant female serves as a surrogate mother during the embryo transfer.

Individual evidence

  1. Mating and reproductive processes in Alfons Willam, Henner Simianer : Tierzucht , Verlag Eugen Ulmer, Stuttgart-Hohenheim, 2011, ISBN 978-3-8252-3526-0 , p. 270
  2. Website of the Embryo Transfer Working Group ( Memento of the original from June 25, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.aet-d.de
  3. Embryo transfer in Germany at the BNV