What is the name of the cavity formed in the gastrula? How does it form in the embryo?

Explanation

**Step-by-Step Solution:**

1. **Identify the Cavity in Gastrula**: The cavity formed in the gastrula is called the **archenteron**.

2. **Understand the Gastrula Stage**: The gastrula is an important stage in embryonic development that occurs after the implantation of the blastocyst in the endometrium lining of the uterus. At this stage, three embryonic germ layers are established: ectoderm, endoderm, and mesoderm.

3. **Formation of the Archenteron**: The archenteron is formed due to the movement of cells during a process known as **morphogenetic movements**.

...