| grade | blastocyst development stage status | | B1 | Blastocoel cavity less than half the volume of the embryo | | B2 | Blastocoel cavity more than half the volume of the embryo | | B3 | Full blastocyst, cavity completely filling the embryo | | B4 | Expanded blastocyst, cavity larger than the embryo, with thinning of the shell | | B5 | Hatching out of the shell | | B6 | Hatched out the shell |
| grade | Inner cell mass (ICM )quality | | 1 | Many cells, tightly packed | | 2 | Several cells, loosely grouped | | 3 | Very few cells |
| grade | Trophectoderm quality | | 1 | Many cells, forming a cohesive layer | | 2 | Few cells, forming a loose epithelium | | 3 | Very few large cells |
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| grade | description | | 1 | blastomeres of equal size, no fragmentation | | 2 | blastomeres of unequal size, <10% cytoplasmic fragments or granular blastomeres | | 3 | blastomeres of unequal size, 10-50% cytoplasmic fragments and granular blastomeres | | 4 | blastomeres of unequal size, >50% cytoplasmic fragments and granular blastomeres |
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