Describe menstrual cycle .

Explanation

### Step-by-Step Solution to Describe the Menstrual Cycle:

1. **Definition of Menstrual Cycle**:
The menstrual cycle is a monthly series of changes that occur in the female body, primarily involving the reproductive system.

2. **Start of the Cycle**:
The menstrual cycle begins with puberty, which is the stage when a girl becomes sexually mature. This typically occurs between the ages of 10 to 13 years.

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