Primary cells divide evenly; No debris
The secondary cells divide evenly; There are some fragments.
Grade 2.5 cells divide evenly with some fragments.
The division of tertiary cells is uneven; There are no fragments or some fragments.
The division of the fourth grade cells is very uneven; The debris is serious.
It should be understood that the generation of debris is a sign of apoptosis. When the embryo is under the pressure of its own reasons or external environment, it will produce DNA repair mechanism, expel harmful cellular components, and lead to the generation of debris. Therefore, the more fragments, the worse the growth potential, which has become an important symbol to judge the quality of an embryo.