Which hormone is secreted by the interstitial tissue of the testes and is responsible for male sex characteristics?

• A. Testosterone
• B. Estrogen
• C. Progesterone
• D. Sperm

Answer: (A)

Testosterone, produced by the interstitial tissue (Leydig cells) of the testes, is the primary hormone that drives male secondary sexual characteristics. It rises during puberty to cause facial and body hair growth, a deeper voice, increased muscle mass, and growth of the genitals. Beyond these changes, testosterone supports spermatogenesis by acting on the seminiferous tubules and Sertoli cells, helping maintain libido and overall male reproductive function. Its production is stimulated by luteinizing hormone from the pituitary, and in some tissues, testosterone is converted to dihydrotestosterone, which has potent effects on certain male characteristics. Estrogen and progesterone are not the main hormones produced by the testicular interstitial tissue, and sperm are cells, not hormones.