Medullary rays are made up of

Options

A. Fibers
B. Tracheids
C. Sclerencyma cells
D. Parenchymatous cells

Answer

**Step-by-Step Solution:**

1. **Understanding Medullary Rays**: Medullary rays are sheets of cells that extend radially from the center of the wood towards the outer part of the plant. They are found in certain woody species and play a role in the transport of nutrients and water.

2. **Identifying the Structure**: These rays appear as radial planar structures that are perpendicular to the growth rings of the wood. This means they run from the center of the tree outward, creating a pattern that can be seen in cross-sections of the wood.

3. **Cell Composition**: Medullary rays are primarily composed of parenchymatous cells. Parenchyma cells are living cells that are involved in various functions such as storage, photosynthesis, and tissue repair.

4. **Transformation of Cells**: Over time, these parenchymatous cells can differentiate into other types of cells, including xylem and phloem cells, which are essential for the plant's vascular system.

5. **Evaluating Options**:
- **Fibers**: These are components of xylem and provide structural support but are not part of medullary rays.
- **Tracheids**: These are also xylem components involved in water transport, not medullary rays.
- **Sclerenchyma Cells**: These are supportive cells with thick walls but do not make up medullary rays.
- **Parenchymatous Cells**: Correct answer, as they are the primary cell type found in medullary rays.

6. **Conclusion**: Therefore, the correct answer is that medullary rays are made up of parenchymatous cells.

**Final Answer**: Medullary rays are made up of parenchymatous cells (Option D).

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