Demi-embryo production from hatching of zona-drilled bovine and rabbit blastocysts
1997
Skrzyszowska, M. | Smorag, Z. | Katska, L.
It is known that the pregnancy rate resulting after transfer of bisected embryos is lower than after transfer of whole embryos. The main reason is the reduced cell number in the demi-embryo which is less than ︣of that in the intact embryo, since a number of blastomeres is damaged as a result of the procedure used in conventional embryo splitting. The aim of our experiment was to develop a non-invasive procedure which would limit cell losses during microsurgery. The experiment was carried out on bovine IVM-IVF embryos at middle, late and expanded blastocyst stage and rabbit embryos at late blastocyst stage cultured in vitro from in vivo produced zygotes. The zona pellucida of these embryos was drilled on the line between the inner cell mass and the trophoblast using a glass microneedle (less than or equal to 2 micrometers) or micropipette (less than or equal to 30 micrometers). The procedure resulted in expulsion of the blastocyst through the perforation and formation of an incomplete demi-embryo configuration, connected by a very thin cell bridge (figure eight in shape). To separate the parts of the embryo, the cell bridge was cut using a glass microneedle. During the separation only a few cells were damaged. As a result of the procedure 4/20 (20.0%), 48/144 (33.3%) and 3/40 (7.5%) middle, late and expanded blastocysts hatched according to the pattern described. The developed procedure could be considered as a non-invasive alternative to conventional embryo splitting.
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