Which term describes embryos in the early cleavage phase from the 2-cell stage up to before morula, often used in ART contexts?

Which term describes embryos in the early cleavage phase from the 2-cell stage up to before morula, often used in ART contexts?

• A. Blastocoele
• B. Cleavage stage embryos
• C. Chimerism
• D. Blastocyst

Answer: (B)

The concept tested is identifying the specific developmental window described as the early cleavage phase after fertilization, when the embryo is undergoing rapid cell divisions from the 2-cell stage up to just before the morula forms. In ART contexts, this period is commonly labeled as cleavage-stage embryos because it covers those successive divisions before the cells compact into a morula. The other terms refer to later stages or unrelated concepts: a blastocyst (and its cavity, the blastocoele) appears after the morula, and chimerism is a genetic condition, not a developmental stage. So cleavage-stage embryos is the precise term for that interval.

The concept tested is identifying the specific developmental window described as the early cleavage phase after fertilization, when the embryo is undergoing rapid cell divisions from the 2-cell stage up to just before the morula forms. In ART contexts, this period is commonly labeled as cleavage-stage embryos because it covers those successive divisions before the cells compact into a morula. The other terms refer to later stages or unrelated concepts: a blastocyst (and its cavity, the blastocoele) appears after the morula, and chimerism is a genetic condition, not a developmental stage. So cleavage-stage embryos is the precise term for that interval.