Three germ layers are formed during which stage of embryonic development :-

Options

A. Morula
B. Blastula
C. Gastrula
D. In any two stages

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the stage of embryonic development during which three germ layers are formed. The options provided are morula, blastula, and gastrula.

2. **Defining Morula**: The morula is a solid mass of cells (blastomeres) that forms after several rounds of cleavage (cell division) of the fertilized egg (zygote). At this stage, the embryo is still a single mass of cells and does not yet have distinct germ layers.

3. **Defining Blastula**: The blastula is formed after the morula stage. It is a hollow sphere of cells (blastomeres) that results from further cleavage of the morula. The blastula is still a single-layered structure and does not contain the three germ layers.

4. **Defining Gastrula**: The gastrula is the stage that follows the blastula. During gastrulation, the single-layered blastula undergoes significant reorganization to form three distinct layers: ectoderm, mesoderm, and endoderm. This process is crucial as these layers will eventually develop into different tissues and organs of the body.

5. **Conclusion**: Since the three germ layers (ectoderm, mesoderm, and endoderm) are formed during the gastrulation phase, the correct answer to the question is the gastrula stage.

**Final Answer**: The three germ layers are formed during the gastrula stage of embryonic development.

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