Notes
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Testosterone is the primary sex masculine hormone.
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It plays several important roles, such as:
- The development of the penis and testes;
- The deepening of the voice during puberty;
- The appearance of facial and pubic hair starting at puberty;
- Muscle size and strength;
- Bone growth and strength;
- Sex drive (libido);
- Sperm production.
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Adolescent boys with too little testosterone may not experience normal masculinization. For example, genitals may not enlarge, and the voice may not deepen normally.
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Signals sent from the brain to the pituitary gland control the production of testosterone in men. The pituitary gland then relays signals to the testes to produce testosterone.
- A feedback loop closely regulates the amount of testosterone in the blood. When testosterone levels rise too high, the brain sends signals to the pituitary to reduce production.
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Testosterone is also essential in females. These hormones are thought to have important effects on ovarian function, bone strength, and sexual behavior.