Which cell junction help to stop substances from leaking across a tissue ?

Options

A. Gap junction
B. Tight junction
C. Desmosomes
D. All of these

Answer

To answer the question "Which cell junction helps to stop substances from leaking across a tissue?", we can follow these steps:

### Step 1: Understand the Types of Cell Junctions
There are several types of cell junctions in animal tissues, including tight junctions, gap junctions, and desmosomes. Each type serves a different function in cellular communication and tissue integrity.

### Step 2: Analyze the Function of Each Junction
- **Gap Junctions**: These junctions allow for the passage of small molecules and ions between adjacent cells. They facilitate communication but do not prevent leakage.
- **Tight Junctions**: These junctions are designed to create a barrier that prevents substances from leaking between cells. They form a seal that restricts the movement of materials across the tissue.
- **Desmosomes**: These junctions provide mechanical strength and allow for some movement between cells but do not primarily function to prevent leakage.

### Step 3: Identify the Correct Junction
From the analysis, it is clear that tight junctions are the ones that prevent leakage of substances across a tissue. They create a nearly impermeable barrier, ensuring that materials must pass through the cells rather than between them.

### Conclusion
The cell junction that helps to stop substances from leaking across a tissue is the **tight junction**.

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