Leydig cells (also called interstitial cells) are found in the testes, located between the seminiferous tubules. Their functions include:
1. Secretion of Testosterone:
- Main source of the male sex hormone testosterone.
- Testosterone regulates spermatogenesis and development of male secondary sexual characteristics.
2. Support in Puberty:
- Helps in the growth of facial hair, deepening of voice, and increase in muscle mass.
3. Maintenance of Male Reproductive Organs:
- Supports the functional integrity of male accessory organs such as the prostate gland and seminal vesicles.
Final Answer:
\[
\boxed{\text{Leydig cells secrete testosterone and maintain male reproductive functions.}}
\]