Blastocyst formation begins about 5 days after fertilization, when a fluid-filled cavity opens up in the morula, a ball consisting of a few dozen cells. The blastocyst has a diameter of about 0.1-0.2 mm and comprises 200-300 cells following rapid cleavage 5-6 days post-fertilization
Blastocyst possesses an Inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoele. The trophoblast gives rise to the placenta.
The use of blastocysts in in-vitro fertilization (IVF) involves culturing a fertilized egg for five days before implanting it into the uterus. It can be a more viable method of fertility treatment than traditional IVF.
DAY 5 EMBRYO (BLASTOCYST STAGE) with Cavity and Inner cell mass in Embryology Lab
What is blastocyst culture?
Blastocyst culture is the process of preserving the embryo in the laboratory inside the culture for 5 days. The embryo is called blastocyst embryo, it is then implanted into the woman’s uterus on the fifth day. For the blastocyst culture to be successful, the doctors place the embryo in sophisticated laboratory and highly skilled biologists handle the process to ensure a healthy embryo transforms into a beautiful baby without any hardship.
What is the monitoring process of the embryos/blastocysts?
The embryologists/biologists examine the embryo everyday to check as how many of them have undergone division and determine the quality. They work in close coordination with the patient and keep them of all the developments of the embryo. When the embryos develops and reaches the blastocyst stage, they incorporate the 3-character grading system which only concentrates on the Inner Cell Mass (ICM), the Trophectoderm (the outermost layer of cells) and to what extent the embryo has grown. In the IVF culture around 60 to 70% of human embryos reach the blastocyst stage only after day 5.Initially multiple eggs (oocytes) might have been fertilised, but not all make their way to the four-cell stage on day two and then the eight-cell stage on day three, and amongst them only few progress and develop into blastocysts. The one that wins is the embryo that has survived and progressed to the current stage, this embryo is tend to be strong, healthy and active. Based on the count and quality of the embryo on day 3 the embryologist will then implant this embryo into the uterus on day 5. Individuals who have less oocytes and amongst them only few fertilized and the division is less by day 3 have no benefits undergoing the blastocyst culture.
Advantages of a blastocyst culture?
The woman’s womb is the best incubator for human embryos but if there are several embryos to choose from on day 3, we clearly know that all cannot make their way till day 5 be it the laboratory or the womb. Placing the embryos in the lab for two extended days reduces the likelihood of implanting a healthy embryo on day 3 which would not survive by day 5. Hence it has greater chances of implanting embryo which has higher success rates and lead to a successful pregnancy. The decision to pick a embryo in between day 3 and day 5 depends on the need of the hour and the situation then. The embryologist shall discuss with the patient. We strongly believe it’s better to wait till day 5 and not worry about the expenses.
Blastocyst culture is appropriate for?
Blastocyst is suitable in cases where the IVF has failed to work. If the IVF was not successful after the embryo was implanted on day 3, blastocyst culture would be helpful to understand if the embryo has to be sustained till day 5 and then implanted.
dvantages for young patients where IVF can work?
Blastocyst culture helps maximize the chances of conceiving as it best determines which embryos can be successful if implanted. We can minimize the threat of multiple pregnancies by inducing a single successful embryo. For women below age 35, who either have female infertility, we can implant single embryo transfer, thus reducing the threat of twins and multiple pregnancy like triplets & quadruples).