Testosterone drives the physical and psychological transformation that teenage boys experience during puberty. The onset and completion of puberty is unique to each person. Male puberty begins as early as age 12 or 13 and completes around age 20. The testicles secrete the majority of male testosterone. The male teenage body may produce as much as the equivalent of 300 milligrams of exogenous testosterone each week.
Testosterone Production
The male body produces 95 percent of its testosterone in the testicles. The hypothalamus and the pituitary gland control the amount of testosterone that that a teenage boy produces. The leydig cells produce testosterone in spaces between the seminiferous tubules inside the testicles. Higher testosterone production in teenagers triggers growth in the testicles and the penis, according to an article posted on BBC Science.
Behavior
A teenage boy's testicles produce 10 times the amount of testosterone during puberty than they produced before puberty. Testicular surges of testosterone in a teenager may transform his interpersonal behavior, and a parent may sense that her teenage son "disappeared." A teenage boy who was communicative may become quiet and monosyllabic during puberty. Surges of testosterone in teenage a boy may reduce his communication and his interest in socializing. A teen boy's testosterone may restrict his interest to athletic or sexual activities. Sexual pursuit, his body parts and female bodies may dominate a teenage boy's desires. Higher levels of testosterone may manifest with higher levels of aggression and dominant male behavior in some teenage boys.
Muscular Development
Hemoglobin transports oxygen molecules to muscle tissue. Higher testosterone in a teenage boy's body increases the amount of hemoglobin that his red blood cells carry. Muscles need a steady supply of oxygen during physical exercise. Higher levels of hemoglobin transport more oxygen to a teenage boy's muscles and he experiences higher levels of strength and fitness than he did prior to his teenage years.
Cellular Growth
Testosterone triggers cellular growth throughout a teenage boy's body. The adam's apple enlarges during teen years. Testosterone contributes to a teenage boy's faster peak growth rate than a teenage girl's peak growth rate. Prominent growth occurs in hard tissues in the arms and legs. Testosterone makes a teenage boy's bones denser than teen girl bones. Testosterone makes a teenage boy's chest and shoulders broad at the final stage of puberty, close to age 20.
Other Sex Characteristics
Teenage boys' testosterone production contributes to several changes in his appearance. Teenage testosterone may trigger hair growth on the face, arms, legs, gonads, torso and back. A teenage boy's voice usually changes and becomes deeper because of higher testosterone levels.
