Embryo Grading

Understanding Embryo Grading?

Embryo grading is a topic that has seen its fair share of debate over the years. Each IVF lab
may have a slightly different way of grading an embryo. For the most part, however, they are all
noting the same features, which are: inner cell mass, trophectoderm, and degree of expansion.

Features of an Embryo

Morphology: Just a fancy word for describing the structure of the embryo.
Morula: After the embryo has done a few rounds of cell division
the cells will compact together in preparation of forming the blastocyst. Compaction means that the cells start to communicate with each other
and cell borders can no longer be defined. This stage usually occurs around late day 3 to day 4 of culture.
Blastocyst: This is the stage of development usually observed on days 5 and 6 of culture. It’s characterized by the presence of an inner cell mass
trophectoderm and blastocoel cavity. Often referred to as a “Blast.”
Inner Cell Mass: Commonly referred to as the “ICM.” This is the little cluster of cells on the interior of the blastocyst that develop into the actual foetus.
Trophectoderm: These are the cells that surround the outside of the blastocyst. They play a role in implantation and eventually become the placenta.