What is a blastocyst?
A blastocyst is a quality embryo that develops on the 5th or 6th day of embryonic development. In this phase, special parts of the embryo are separated, which so far had only clusters of cells, so that the embryo in the blastocyst phase has separate regions.
Trofektoderm (outer layer of cells)
ICM (Inner cell mass)
Blastocoel (inner cavity filled with fluid)
The ICM or embryoblast represents the original stem, the embryonic cells from which the fetus will develop, the trophectoderm represents the trophoblast which will serve as the basis for the formation of the placenta in later embryonic development.
What is blastocyst culture?
Blastocyst culture involves prolonged monitoring of embryos in vitro to the stage where they pass into the blastocyst.
Recently, embryo transfer with blastocysts has gained in popularity in all IVF processes due to the greater implantation potential of blastocysts compared to embryos 3 days of development.
In vivo implantation of embryos in the uterus is in the blastocyst phase, in order to optimize the development of embryos in laboratory conditions, special attention should be paid to details in incubators that will favor the development of quality blastocysts (use sequential media, well regulated pH, etc.)
Under IVF culture conditions, only about 60 to 70% of human embryos progress to the blastocyst stage after 5 days in younger people (under 35 years of age). A few oocytes may have initially fertilized, but not all will progress to the four-cell stage on the second day and the eight-cell stage on the third day in culture, and even fewer will develop into blastocysts.
Simply put, this process of self-selection can be seen as the "survival of the fittest." Embryos that survive to this stage of development are more likely to be strong, healthy and robust. Depending on the number and quality of embryos on day 3 and the patient's medical history, the embryologist will recommend whether embryo culture should be monitored to the blastocyst stage or embryo transfer should be performed on day 3 of embryonic development.
When you go on an embryo transfer with blastocysts
- There is a statistically significant difference in pregnancy and the birth of a healthy baby with blastocyst embryo transfer
- Reduces chromosomal abnormalities of the embryo. Although some genetic malformations such as mosaicism and trisomnia may be present in a well-graded blastocyst, their chance is significantly lower than in embryos on day 3 of embryonic development.
- When it is necessary to do embryo transfer of 1 embryo
• Embryo biopsy is much more suitable in the blastocyst stage because more cells can be taken for DNA analysis, the appearance of mosaicism is reduced, ICM (future fetus) part remains completely intact