In biology embryo is a multicellular organism that’s in its early stages of development and growth from a single egg to maturity. Another word for embryo screening is PGD. PGD stands for pre-implantation genetics diagnosis. People usually use PGD to check their embryos for any diseases and they can chose which embryo they want that does not have a disease. Now they have used PGD to select the gender of their embryo and there currently trying to figure out out how to select the traits of the embryo. In a human, it's called an embreyo until about eight week after it's fertilization. Some locations where you can have a PGD procedure are as followed:
"Complex processes bring sperm to the immediate area of the egg (see reproduction). A single sperm will penetrate the egg's membrane, and the sperm nucleus will enter the egg interior and fuse with the egg nucleus. The result is a fertilized egg, or zygote. The first period of actual development is characterized by rapid sequential division of the egg into many small cells, or blastomeres.Growth usually does not occur during cleavage." The cleavage process ends with the formation of the blastula stage. Genetic testing, including diagnostic & carrier testing and prenatal diagnosis, helps families have the courage to risk having future children and to avoid the recurrence of devastating disease. PGD includes removing an embryo, doing a genetic test on it, and then they either put the embryo back after the testing, or if it has a diesease, illness, or it's messed up, they freeze it and then throw it away. In humans, PGD was developed in the United Kingdom in the mid 1980s as an alternative to current prenatal diagnoses. Initially, PGD revolved around determination of gender as an indirect means of avoiding an X-linked disorder.
Blastomeres are a cell formed by cleavage of a fertilized ovum (A mature female reproductive cell). Cleavage is referred to the division of cells in the early embryo.