64 Collection and cultivation of embryos in vivo and in vitro

Typically, embryos are cultured until having reached the 6–8 cell stage three days after retrieval. In many Canadian, American and Australian programmes[citation needed], however, embryos are placed into an extended culture system with a transfer done at the blastocyst stage at around five days after retrieval, especially if many good-quality embryos are still available on day 3. Blastocyst stage transfers have been shown to result in higher pregnancy rates.[1] In Europe, transfers after 2 days are common.

Culture of embryos can either be performed in an artificial culture medium or in an autologous endometrial coculture (on top of a layer of cells from the woman's own uterine lining). With artificial culture medium, there can either be the same culture medium throughout the period, or a sequential system can be used, in which the embryo is sequentially placed in different media. For example, when culturing to the blastocyst stage, one medium may be used for culture to day 3, and a second medium is used for culture thereafter.[2] Single or sequential medium are equally effective for the culture of human embryos to the blastocyst stage.[3] Artificial embryo culture media basically contain glucose, pyruvate, and energy-providing components, but the addition of amino acids, nucleotides, vitamins, and cholesterol improve the performance of embryonic growth and development.[4] Methods to permit dynamic embryo culture with fluid flow and embryo movement are also available.[5] A new method in development uses the uterus as an incubator and the naturally occurring intrauterine fluids as culture medium by encapsulating the embryos in a permeable intrauterine vessel.[6]

A review in 2013 of studies on individual culture media came to the result that the G3 medium confers a significantly higher live birth rate and a lower risk of low birthweight than the Sydney IVFmedium.[7]

Usage of low oxygen concentrations of 5% rather than about 20% in the atmosphere has been shown to increase live birth rate to a relative probability of 1.24, without any evidence of increased risk for multiple pregnancies, miscarriages or congenital abnormalities.[8]

65	)Methods of embryo transplantation

Embryo is now one of the most pressing issues in the field of animal farming. With the help of embryo transfer can dramatically increase the yield of the progeny of high-producing cows. Embryo or embriotechnology is to obtain one or more embryos from the uterus of breeding animals (donors) and transplant the uterus of cows (retsepient), where embryos develop to calving. This method, combined with superovulation in donors can get a great seed of high yielding animals. In this way the embryos can be implemented in either breed in other regions, using as retsepient beef cows. This method also facilitates the exchange of agricultural gene pool of animals between countries and continents. Embryo transfer can be used to produce offspring from valuable, but barren cows that have lost the ability to grow as a result of accident, illness or age.

When it was established that the rabbit has immunity against FMD, put forward the idea of ​​using the method for the recovery of transplant pups of foot and mouth disease of animals. Genital tract of the rabbit, which transplanted embryos can destroy FMD virus in embryos. Transplantation can be used for temporary storage of embryos. In the oviducts of rabbits can carry transcontinental transport of sheep embryos.

Removing the embryos until the 70s produced mainly by surgery, he was subsequently replaced by a less traumatic and time-consuming non-surgical, based on the introduction of a special probe into the uterus through the natural channel. The probe has three channels. One channel is for inflating the balloon that occludes the uterine horn, preventing leakage of fluid. According to another input channel saline at 25-30C, and the embryos are washed back with them through the third channel of the probe into the tube placed in a waterbath at 35C. From this liquid extracted embryos. On average superovulation of donor can be from 5 to 7 embryos.

Transplantation is carried out with the help of a special probe or a gun for insemination. Embryos were placed in the uterine horn. Pregnancy in females - retsepient checked on the level of progesterone in plasma on day 21.

Regulation of sex. In the practice of breeding animals is very important to learn to manage education in the offspring of male and female individuals. The method of separation of embryos by sex based on determining specific proteins males. This method is widely used in animal practice in many countries. In Canada since 1975 born calves, separated by sex on stage embryos. In the long term to get targeted individuals, male or female can be used microsurgical technique replace the X and Y chromosomes. Such manipulations are carried out on the plant cells and amphibian oocytes.