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1

Factors influencing quality and quantity of in vitro produced bovine embryos

100%
Katska L.
Biotechnologia
|
1998
|
issue 2
110-118
EN
In vitro production of bovine embryos has become a routine, increasingly available technology. Presently this technique can yield approximately 40% of blastocysts in relation to the number of oocytes used for in vitro maturation and fertilization. However, available data indicate that in vitro produced bovine embryos are more susceptible to freezing and subject to a higher incidence of fetal loss following transfer. The comparison between in vivo (sheep oviducts) and in vitro (co-culture with somatic cells) embryo culture conditions revealed that in vivo conditions are superior in terms of quality of embryos. The factors influencing quantity and quality of in vitro produced embryos, i.e. the size of ovarian follicle for immature oocytes recovery, methods of oocytes recovery, morphology of immature oocytes, bull effect on IVF and possible ways to overcome these limitations as well as the effect of different embryo culture systems have been discussed.
2

Methods for obtaining in vitro oocytes and embryos in mammals - possibilities and limitatios

100%
Katska L.
Biotechnologia
|
1995
|
issue 3
33-43
EN
The autors discuss methods through which the reproductive potentialin cattle may be increased.Two procedures for mass production of embryos to be used in cattle breeding schemes are now available, namely superovulation and embryo transfer, nd more recently in vitro embryo production.Hormonal treatmentfor multiple ovulation, nonsurgical embryo collection and embryo transfer are widespread techniques to obtain more offspring from genetivally superor cattle (MOET program).However,the cost can br high and the yield of embryos is unpredictable.
3

Improvement of female reproductive potential by in vitro embryo production technology

100%
Katska L.
Biotechnologia
|
1996
|
issue 2
95-105
EN
Two procedures for mass production of embryos for use in cattle breeding schemes are now available, namely multiole ovulation + embryo transfer and more recently in vitro embryo production. Hormonal treatment for multiple ovulation, nonsurgical embryo collection and embryo transfer are widespread techniques to obtain more offspring from genetically superior cattle (MOET programme).However, the costs can be considerable and the yield of embryos is highly variable.Research during the past decade has been focused on embryo production in vitro with oocytes from slaughterhouse ovaries and has tremendously succeed.Presently ultrasound guided technique for oocyte collection in living animals has been developed.However, both discussed procedures allow to use only a tiny part of high follicular capital of ovary.Bovine ovary contains many thousands of primordial follicles, but the vast majority become atretic during growth and maturation.Recently is developed a technique for in vitro growth of prenatal follicles rescuing them against atresia.It would offer a significant means for the propagation of valuable animal stocks and would be an addition to the methods already available for use in embryo production in vitro, since it would supply a large and uniform population of oocytes from genetically superior animals.
4

Factors affecting production of transgenic farm animals: cattle and rabbits

39%
Jura J., Smorag Z., Katska L., Skrzyszowska M., Gajda B., Rynska B.
Biotechnologia
|
1998
|
issue 2
101-109
EN
There are many factors affecting transgenic farm animals production. One of them is the effectiveness of the transfer of zygotes and embryos obtained after DNA microinjection. Low effectiveness of the transfer of potentially transgenic blastocysts in cattle is due to their decreased developmental potential in comparison to the blastocysts developed from not microinjected zygotes. A simple short term in vitro culture used for rabbit zygotes after microinjection increased twice the number of produced potentially transgenic rabbits.
5

Influence of DNA concentration on the efficiency of bovine blastocyst production after WAP-bGH microinjection into germinal vesicle of immature oocytes, zygotes and embryos obtained in vivo or in vitro

39%
Jura J., Smorag Z., Katska L., Skrzyszowska M., Houdebine L.-M., Rynska B.
Biotechnologia
|
1997
|
issue 4
71-81
EN
Microinjection is one of the most successfully used methods to produce transgenic farm animals. But the effectiveness of transgenesis with the use of microinjection, specially in cattle is still low. Many steps of the transgenesis has been found to influence its effectiveness; DNA purity, the site of its injection, the culture system. There are no reports on the influence of a DNA vector concentration influence on the developmental ability of transformed bovine eggs to the blastocyst stage in the in vitro culture. In presented experiments we investigated the influence of different DNA concentrations on the developmental rate of microinjected immature bovine oocytes, zygotes and 2-cell embryos to the blastocyst stage.
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