Living structures passing through the cell wall at the region of primary pit fields are called as

Options

A. Plasma membrane
B. Microtubules
C. Cytoskeleton
D. Plasmodesmata

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about a living structure that passes through the cell wall at the primary pit fields.

2. **Identifying Cell Wall Layers**: The plant cell wall consists of three layers: the primary wall, the middle lamina, and the secondary wall. The primary pit fields are areas in the primary wall where cell connections occur.

3. **Role of Middle Lamina**: The middle lamina is a layer that connects adjacent plant cells. It is rich in pectin, which helps to cement the cells together.

4. **Formation of Plasmodesmata**: The connections that form between adjacent cells at the primary pit fields are called plasmodesmata. These are cytoplasmic channels that allow for communication and transport between cells.

5. **Composition of Plasmodesmata**: Plasmodesmata are formed by the middle lamina, which is rich in pectin, specifically calcium and magnesium pectates.

6. **Identifying the Correct Answer**: Among the options provided (plasma membrane, microtubules, cytoskeleton, and plasmodesmata), the correct answer is **plasmodesmata**, as it is the living structure that passes through the cell wall at the primary pit fields.

### Final Answer:
The living structures passing through the cell wall at the region of primary pit fields are called **plasmodesmata**.

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