IVF Collapsed Expanded Blastocyst.

IVF Collapsed Expanded Blastocyst.
While the thin zona pellucida is still intact, the blastocele of the embryo on the bottom has collapsed (Code 1). The top two embryos are Code 4 because of the stage of development is retarded for their age (day 8). [Code 1: excellent or good; Code 2: fair; Code 3: poor; Code 4: dead or degenerating].

Hansen PJ (2006)