What is a characteristic of the gastrula stage of embryo development?

• A. Formation of the blastocoel
• B. Establishment of the three germ layers
• C. Implantation into the uterine wall
• D. Cleavage divisions

Answer: (B)

Verified step by step guidance

1. Understand the stages of embryonic development: The gastrula stage follows the blastula stage and is crucial for establishing the basic body plan of the embryo.
2. Identify the key process during the gastrula stage: The formation of the three germ layers—ectoderm, mesoderm, and endoderm—is a defining characteristic of this stage.
3. Differentiate between the processes: Formation of the blastocoel occurs during the blastula stage, not the gastrula stage.
4. Recognize the role of the three germ layers: These layers give rise to all tissues and organs in the body, making their establishment a critical event in development.
5. Clarify the timing of implantation: Implantation into the uterine wall typically occurs before the gastrula stage, during the blastocyst stage.