Testes: Functions in Sperm Production, Hormone Regulation, and Male Development

The testes (testicles) are the primary male reproductive organs, serving both exocrine (sperm) and endocrine (hormone) functions.

1. Spermatogenesis

Continuous sperm production in seminiferous tubules (64–72 day cycle). Requires testosterone and FSH. Sperm mature in epididymis.

2. Testosterone Production

Leydig cells produce testosterone under LH stimulation. Functions:

• Male sexual differentiation (fetal life)
• Puberty: secondary sexual characteristics (voice, hair, muscle, bone)
• Adult: libido, erectile function, spermatogenesis support, metabolic health, mood, cognition

3. Inhibin Secretion

Sertoli cells produce inhibin B, providing negative feedback on FSH.

4. Regulation

Hypothalamic-pituitary-gonadal axis: GnRH → LH/FSH → testicular function. Negative feedback by testosterone and inhibin.

Clinical Relevance

• Hypogonadism: primary (testicular) vs. secondary (pituitary/hypothalamic)
• Infertility evaluation includes semen analysis, hormones
• Testicular cancer: most common solid tumor in men 15–35; high cure rate

Testicular health is integral to male reproductive and overall health.