At around week seven in utero, the sex-related gene on the Y chromosome initiates the development of the testicles in male infants. Healthcare providers use synthetic testosterone to treat and manage various medical conditions. Natural testosterone is a steroid — an anabolic-androgenic steroid. Testosterone is the main androgen, meaning it stimulates the development of male characteristics. Testosterone is a hormone that your gonads (sex organs) mainly produce. Hormones are chemical messengers that trigger necessary changes in the body. From sinus infections and high blood pressure to preventive screening, we’re here for you. Your healthcare provider will let you know if you need further tests. Excess testosterone affects your body differently depending on your sex and age. It’s important to note that the normal ranges for testosterone levels can vary based on the type of blood test done and the laboratory where it is done. Your body controls the levels of testosterone in your blood. However, the majority of testosterone produced in the ovaries is converted to the primary female sex hormone, estradiol. "Anabolic" refers to muscle building, and "androgenic" refers to increased male sex characteristics. Some effects are reversible once a person stops the treatment. When a person receives treatment for gender dysphoria, they may also begin to feel more like themselves and more comfortable in their own body. At age 16 years or younger, additional paperwork is necessary for people to access such therapy. A link has also been found between relaxation following sexual arousal and testosterone levels. Men who watch a sexually explicit movie have an average increase of 35% in testosterone, peaking at 60–90 minutes after the end of the film, but no increase is seen in men who watch sexually neutral films. In non-human primates, it may be that testosterone in puberty stimulates sexual arousal, which allows the primate to increasingly seek out sexual experiences with females and thus creates a sexual preference for females. The reflexive testosterone increases in male mice is related to the male's initial level of sexual arousal. When testosterone-deprived rats were given medium levels of testosterone, their sexual behaviours (copulation, partner preference, etc.) resumed, but not when given low amounts of the same hormone.
