In this picture, you can see the aspiration pipette (the glass tube on the right) gently pulling the single blastomere off of an 8 cell embryo.
At this early point of embryo development, all of the cells are equivalent and thus, removal of a cell from the embryo at this stage does not remove anything critical for normal development. The embryo compensates for the removed cell and should continue to divide following blastomere biopsy.
After obtaining cells from the embryo, they can then be analyzed using a variety of different techniques. It doesn't matter which of the eight cells was removed because as the embryo divides, each subsequent generation of cells contains exactly the same genetic information as the "parent" cell. This, each of the eight cells should be identical.
However, at times there can be an aberration in the cell division in which one or more of the "daughter" cells ends up being slightly different from the parent cell. This is called mosaicism. Mosaicism is important when performing preimplantation genetic diagnosis - PGD via blastomere biopsy because it means it is possible that the cell that is biopsied may not be representative of the entire embryo. For example, if during PGD, a blastomere biopsy is performed and the cell that is obtained is abnormal, the entire embryo would considered abnormal even though the remaining cells in the embryo may be normal. The opposite is also true. An embryo with 7 abnormal cells and one normal can be considered normal if the "eighth" cell happens to be the one that is biopsied.
There are some studies which suggest that the potential of an embryo to implant in the uterus might be slightly reduced by performing blastomere biopsy especially if performed by an inexperienced technician.
|Last Updated ( Friday, 05 November 2010 )|