Question

which of the following is a tightly packed sphere of blastomeres that has reached the uterus but has not yet implanted itself? a.) blastocyst b.) blastomere c.) morula d.) trophoblast

Explanation:

• Blastocyst: A blastocyst is a structure that forms after the morula stage. It has an inner cell mass and a trophoblast layer. It implants in the uterus.
• Blastomere: A blastomere is a single cell of the early - stage embryo (cleavage stage), not a sphere of cells.
• Morula: A morula is a solid (tightly - packed) sphere of blastomeres. It reaches the uterus before implantation.
• Trophoblast: The trophoblast is a part of the blastocyst (outer layer) that is involved in implantation and placental formation, not a sphere of blastomeres.

Answer:

C. Morula