What is a blastocyst?
The fertilization of the egg by a sperm in the human body occurs after its separation from the ovary (ovulation), which forms an embryo from a single cell (the zygote), which contains genetic material from the sperm and the egg. After that, the zygote divides progressively and turns into a multicellular embryo. When the embryo contains 12-16 cells, it is called a “cell”. After 5-6 days, the embryo contains a multiple cells and forms a hollow in the center. In this stage the embryo is called ”blastocyst” and is gone through the first step of differentiation – division into two types of tissues, trophectoderm and internal cellular tissue. Trophectoderm later will forms the placenta, and the inner cellular will form the fetus. In the human body, the fertilized body is placed in the fallopian tube, close to the ovary. The developing embryo goes down through the tube in the uterus about three to four days after ovulation, when it is in stage „morula”. Embryo stays in the uterus for about 2 days, when it develops into blastocyst. The blastocyst is implanted in the endometrial mucosa around the fifth or sixth day after ovulation, so that it can develop water supply (placenta), which will occur in the placenta.
What is cultivation to the blastocyst stage?
This is a method, in which the fertilized eggs, so called embryos, are cultivated for 120 hours in special environment with the purpose for optimal selection. The cultivating allows us to choose the embryos with a better biological potential, on the other hand – it helps prevent the development of big percent of the genetically damaged embryos.
The advantages of blastocyst transfer:
The transfer occurs closer in time to the natural process, in which the embryo enters the uterus – when the uterine lining can provide a better environment for the embryo. The laboratory maintaining of the embryos for a longer period of time allows us to choose the healthiest embryos, which have a better chance of implanting. This way we can put back a smaller number of embryos in the uterus, which decreases the chance of multiple fertilization.
The risks of the blastocys transfer:
The main risk the chance of death of some of the embryos in laboratory conditions, before reaching the blastocyst stage. In some couples, it is possible for all embryos to die and the transfert to fail.