At maturiity, which of the following is non-pnucleated?

Options

A. Sieve cell
B. Companion cell
C. Palisade cell
D. Cortical cell

Answer

To determine which of the following cells is non-nucleated at maturity, we will analyze each option provided:

1. **Semen Cell**: Sperm cells are typically nucleated. They contain genetic material necessary for fertilization. Therefore, this option is not correct.

2. **Companion Cell**: Companion cells are specialized parenchyma cells that are associated with sieve tube elements in the phloem of flowering plants. They are nucleated and play a role in the transport of nutrients. Thus, this option is also not correct.

3. **Palisade Cell**: Palisade cells are found in the mesophyll of leaves and are responsible for photosynthesis. They contain a nucleus and are therefore not non-nucleated.

4. **Cortical Cell**: Cortical cells are found in the cortex of stems and roots. They are also nucleated and involved in storage and transport functions.

After analyzing all the options, it is important to note that the only cell type that is non-nucleated at maturity is the **sieve tube element**, which is a type of cell found in the phloem. However, since "sieve tube element" is not listed as an option, we can conclude that the question may have intended to refer to the **sieve cell** (which is often confused with the term "seway cell" mentioned in the transcript).

Thus, the correct answer is that the **sieve cell** (or sieve tube element) is non-nucleated at maturity.

### Step-by-Step Solution:
1. **Identify the options**: The options provided are semen cell, companion cell, palisade cell, and cortical cell.
2. **Analyze each option**:
- **Semen Cell**: Nucleated.
- **Companion Cell**: Nucleated.
- **Palisade Cell**: Nucleated.
- **Cortical Cell**: Nucleated.
3. **Determine the non-nucleated cell**: The only cell type that is non-nucleated at maturity is the sieve cell (or sieve tube element).
4. **Conclude the answer**: Since none of the options explicitly mention the sieve cell, we conclude that the question may have intended to refer to it.

### Final Answer:
The correct answer is the **sieve cell** (or sieve tube element), which is non-nucleated at maturity.