Blastocyst
Updated:A blastocyst is an early stage of embryonic development that occurs about 5-6 days after fertilization. It's a hollow ball of cells consisting of an outer layer called the trophoblast, which will eventually form the placenta, and an inner cell mass that will develop into the fetus. The blastocyst stage is crucial for successful implantation in the uterus and the beginning of pregnancy.
Additional Information
The blastocyst is formed through a process called blastulation, where the fertilized egg (zygote) undergoes rapid cell division. At this stage, the embryo is about 0.1-0.2 mm in diameter and contains approximately 200-300 cells. The blastocyst's ability to implant in the uterine wall is a critical factor in determining whether a pregnancy will be successful.
Examples
During in vitro fertilization (IVF), embryos are often cultured to the blastocyst stage before being transferred to the uterus, as this can increase the chances of successful implantation.
Some couples undergoing fertility treatments may opt for genetic testing of their embryos at the blastocyst stage to screen for chromosomal abnormalities.