Depending on the grade of expansion of blastocyst embryos, we can distinguish between:
- Early blastocyst
- The blastocoel starts to be visible.
- Cavitating blastocyst
- The trophoblast and the inner cell mass can be seen.
- Expanded blastocyst
- The blastocyst has increased in size and the zona pellucida (ZP) becomes thinner.
- Hatching blastocyst
- The blastocyst starts to hatch out of the ZP.
- Hatched blastocyst
- The blastocyst is already completely hatched.
By Ana Mª Villaquirán Villalba MD, MSc (gynecologist), José Luis de Pablo BSc, MSc, PhD (senior clinical embryologist), Rebeca Reus BSc, MSc (embryologist) and Sandra Fernández BA, MA (fertility counselor).
Last Update: 05/28/2018