Rearrangement of layers/morphogenetic movements occur during Gastrualtion

Answer

**Step-by-Step Solution:**

1. **Understanding Gastrulation**: Gastrulation is a crucial phase in embryonic development that follows the blastula stage. During this phase, the single-layered blastula reorganizes into a multi-layered structure known as the gastrula.

2. **Formation of Germ Layers**: During gastrulation, three primary germ layers are formed: the ectoderm, mesoderm, and endoderm. Each of these layers will eventually give rise to different tissues and organs in the developing organism.

3. **Morphogenetic Movements**: The process of gastrulation involves various morphogenetic movements, which are movements of cells that lead to the rearrangement of these germ layers. These movements include invagination, involution, and epiboly, which help in the proper positioning of the germ layers.

4. **Rearrangement of Layers**: As the cells undergo these morphogenetic movements, they rearrange themselves to form the distinct layers of the gastrula. This rearrangement is essential for the proper development of the embryo.

5. **Conclusion**: Therefore, the rearrangement of layers and morphogenetic movements occur during gastrulation, making it the correct answer to the question.

**Final Answer**: The rearrangement of layers/morphogenetic movements occur during **Gastrulation**.

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