Expanded Hatched Blastocyst.

Expanded Hatched Blastocyst.
Collected on Day 7, this blastocyst (Stage 8) has re-expanded after shedding the zona pellucida (hatching). The inner cell mass is clearly delineated at the top of the image. Trophoblastic cells can be identified. Code 1 (excellent).

Drost M (1984)