The process during which tight junctions form between juxtaposed blastomeres, resulting in a solid mass of cells with indistinguishable membranes, is called what?

The process during which tight junctions form between juxtaposed blastomeres, resulting in a solid mass of cells with indistinguishable membranes, is called what?

• A. Corona Radiata cells
• B. Cryopreservation
• C. Complex aneuploidies
• D. Compaction

Answer: (D)

Compaction is the process where blastomeres form tight junctions and adhere tightly to each other, creating a solid, smooth-surfaced mass. This typically happens around the 8-cell stage, as cells flatten against one another and establish strong cell–cell adhesion (primarily via E-cadherin). The intercellular spaces diminish, so the membranes between neighboring cells become indistinguishable, forming the compact morula. This tight, cohesive arrangement is a key step before the embryo transitions to the blastocyst stage, with the outer cells and inner cell mass differentiating later. The other options describe structures or processes not involved in this cell–cell adhesion event: corona radiata cells surround the oocyte before fertilization, cryopreservation is freezing biological material, and complex aneuploidies refer to chromosomal abnormalities.

Compaction is the process where blastomeres form tight junctions and adhere tightly to each other, creating a solid, smooth-surfaced mass. This typically happens around the 8-cell stage, as cells flatten against one another and establish strong cell–cell adhesion (primarily via E-cadherin). The intercellular spaces diminish, so the membranes between neighboring cells become indistinguishable, forming the compact morula. This tight, cohesive arrangement is a key step before the embryo transitions to the blastocyst stage, with the outer cells and inner cell mass differentiating later. The other options describe structures or processes not involved in this cell–cell adhesion event: corona radiata cells surround the oocyte before fertilization, cryopreservation is freezing biological material, and complex aneuploidies refer to chromosomal abnormalities.