What is the thickening present in collenchyma cell called?

Explanation

**Step-by-Step Solution:**

1. **Understanding Collenchyma Tissue**: Collenchyma is a type of simple permanent tissue in plants that provides support and flexibility. It is characterized by its living cells that are elongated and closely packed together.

2. **Identifying Cell Structure**: The cells in collenchyma tissue have irregularly thickened cell walls, particularly at the corners where the cells meet.

3. **Recognizing the Thickening**: The thickening present in collenchyma cells is primarily located at the corners of the cell walls.

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