Give two striking similarities in the sequence of embryonic development of all the vertebrates

Explanation

### Step-by-Step Solution:

1. **Understanding Embryonic Development**: The embryonic development of vertebrates follows a series of stages that are remarkably similar across different species. The two key stages to focus on are the blastula and gastrula stages.

2. **Formation of Blastula**:
- The first striking similarity is the formation of the blastula, which occurs after fertilization.
- In vertebrates, the blastula is typically composed of 30 to 60 cells and has a fluid-filled cavity known as the blastocoel.
- The outer layer of the blastula is called the trophoblast, which provides nutrition and protection to the developing embryo.
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