Intercellular junction which helps in exchange of substances is :

Options

A. Tight junction
B. Gap junction
C. Interdigtation
D. Desmosome

Answer

To answer the question "Intercellular junction which helps in exchange of substances is:", we can follow these steps:

### Step 1: Understand the Types of Intercellular Junctions
There are several types of intercellular junctions in epithelial tissues, each serving different functions. The main types include tight junctions, gap junctions, interdigitations, and desmosomes.

### Step 2: Analyze Tight Junctions
Tight junctions, also known as zona occludens, are found in the apical part of adjacent epithelial cells. They are characterized by tightly packed membranes that fuse together, preventing the leakage of substances between cells. Therefore, they do not facilitate the exchange of substances.

**Hint:** Tight junctions prevent substance leakage and do not allow exchange.

### Step 3: Examine Gap Junctions
Gap junctions are specialized connections between adjacent cells that contain small gaps. These junctions allow for the direct exchange of ions and small molecules between cells, facilitating communication and substance exchange.

**Hint:** Gap junctions are designed for chemical exchange between adjacent cells.

### Step 4: Consider Interdigitation
Interdigitation refers to the interlocking of adjacent cells through finger-like projections. While they increase the surface area for adhesion, they do not primarily function for the exchange of substances.

**Hint:** Interdigitation enhances adhesion, not substance exchange.

### Step 5: Review Desmosomes
Desmosomes, also known as macula adherens, are structures that provide mechanical strength to tissues by anchoring cells together. They do not facilitate the exchange of substances.

**Hint:** Desmosomes are for adhesion and mechanical strength, not exchange.

### Step 6: Identify the Correct Answer
Based on the analysis, the intercellular junction that helps in the exchange of substances is the **gap junction**.

**Final Answer:** The intercellular junction which helps in exchange of substances is **gap junction**.