The cell membranes of adjacent cells are fused at

Options

A. macule aderens
B. zonula adherens
C. zonula occludens
D. nexus

Answer

To answer the question "The cell membranes of adjacent cells are fused at," we need to analyze the options provided and understand the characteristics of each type of cell junction.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the type of junction where the cell membranes of adjacent cells are fused. This implies a strong connection that prevents the passage of materials between cells.

2. **Analyzing the Options**:
- **Maculae Adherens (Desmosomes)**: These are specialized structures that provide adhesion between cells but do not fuse the membranes. They are more like spot welds that hold cells together.

- **Zonula Adherens**: This type of junction is also involved in cell adhesion, but it does not completely fuse the membranes. It uses proteins like E-cadherin to help cells stick together, but there are still spaces between the cells.

- **Zonula Occludens (Tight Junctions)**: These junctions are characterized by the fusion of the cell membranes of adjacent cells. They create a barrier that prevents the leakage of materials between cells, effectively sealing the space between them.

- **Nexus (Gap Junctions)**: These are specialized areas that facilitate communication between cells by allowing small molecules and ions to pass through. They do not fuse the membranes but rather create channels between cells.

3. **Identifying the Correct Answer**: Based on the analysis, the junction where the cell membranes of adjacent cells are fused is the **Zonula Occludens (Tight Junctions)**.

4. **Final Answer**: The correct answer is **Zonula Occludens**.