Which term describes embryos beginning with the 2-cell stage up to, but not including, the morula stage?

Which term describes embryos beginning with the 2-cell stage up to, but not including, the morula stage?

• A. Birth (single)
• B. Cleavage stage embryos
• C. Blastocoele
• D. Chimerism

Answer: (B)

Early embryogenesis involves a rapid series of cell divisions without growth, known as cleavage. This process takes the embryo from the 2-cell stage through 4-cell, 8-cell, and continues until the morula forms. So the term for embryos from the 2-cell stage up to, but not including, the morula stage is cleavage-stage embryos. The other terms refer to later structures or unrelated concepts: blastocoele is the fluid-filled cavity inside a blastocyst (a stage after the morula), and chimerism is a genetic condition involving two different cell lineages. Birth (single) is not an embryonic developmental stage.

Early embryogenesis involves a rapid series of cell divisions without growth, known as cleavage. This process takes the embryo from the 2-cell stage through 4-cell, 8-cell, and continues until the morula forms. So the term for embryos from the 2-cell stage up to, but not including, the morula stage is cleavage-stage embryos. The other terms refer to later structures or unrelated concepts: blastocoele is the fluid-filled cavity inside a blastocyst (a stage after the morula), and chimerism is a genetic condition involving two different cell lineages. Birth (single) is not an embryonic developmental stage.