Mention the most significant function/role of the following:
Interstitial cells of testis

Explanation

### Step-by-Step Solution:

1. **Identify the Location**: The interstitial cells of the testis are located in the spaces between the seminiferous tubules within the testis.

2. **Differentiate Cell Types**: There are two main types of cells in the testis: Sertoli cells and Leydig cells. The interstitial cells specifically refer to Leydig cells.

3. **Function of Leydig Cells**: The primary function of Leydig cells (interstitial cells) is the production and secretion of testosterone, which is the main male sex hormone.

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