The blastocyst stage is normally reached by day 6 to 7 after in-vitro fertilization. Both embryos are Stage 6 and Code 1. The blastocele is starting to noticeably enlarge in the blastocyst on the right. [Code 1: excellent or good; Code 2: fair; Code 3: poor; Code 4: dead or degenerating].
Hansen PJ (2006)