What are the changes that take place in the uterus during the menstrual phase?

Explanation

### Step-by-Step Solution:

1. **Understanding the Menstrual Phase**: The menstrual phase is a part of the menstrual cycle that typically lasts between 3 to 7 days. It is characterized by the shedding of the uterine lining.

2. **Breakdown of the Endometrium**: During this phase, the endometrium (the inner lining of the uterus) begins to break down. This breakdown is a response to hormonal changes in the body when there is no fertilization of the ovum.

3. **Shedding of the Endometrium**: As the endometrium breaks down, it is shed from the uterus. This shedding is what constitutes menstrual bleeding. The blood and tissue are expelled from the body through the vagina.

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