The first sign of puberty in males is enlargement of the testicles.  This is followed by enlargement of the penis and then the development of pubic hair.  Other changes that occur in puberty of males include: acne, underarm and chest hair, facial hair, underarm perspiration, body odor and deepening of the voice.  There is wide variation in the time of onset of puberty but it typically begins between the ages of 9 and 14 years.  Boys often have a growth spurt during puberty with the most rapid growth occurring around the time of the development of underarm hair.  Puberty can be an emotionally charged time in a boys life as he wrestles questions of sexuality, morality, self image, independence, conformity and relationships.

What is puberty?

Puberty is the time in life when a child enters adolescence.  Multiple changes in the body occur that prepare a child for future reproduction.

How does puberty start?

The exact mechanism of puberty is not fully understood, however puberty begins with hormone signals from the brain.  The pituitary gland in the brain becomes more sensitive to gonadotropin-releasing hormone (GnRH), which leads to release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).  The testicles respond to these hormones by producing testosterone, which directly stimulate the body tissues to change.

What is the progression of testicle and penis enlargement?

The first sign of puberty in males is enlargement of the testicles.  This is followed by enlargement of the penis and then development of pubic, underarm, chest, and facial hair.  Testicle and penis development is classified into 5 distinct stages (the so called Tanner stages). 

Tanner stage 1 (preadolescent) - Prior to puberty.  No testicle or penis enlargement. 

Tanner stage 2 (ages 12.5 to 14.5) - Puberty typically starts with enlargement of the testicles.  The skin of the scrotum (the sac that holds the testicles) reddens and attains a rougher texture.  The penis may begin to have slight enlargement.

Tanner stage 3 (ages 13 to 15)  - The penis increases in length.  The testicles and scrotum continue to enlarge.

Tanner stage 4 (ages 13.5 to 15.5)  - The penis increases in width and the glans (the end of the penis) enlarges and develops further.  The testicles and scrotum continue to enlarge and the skin of the scrotum darkens.

Tanner stage 5 (ages 14 to adult)  - The penis and testicles have an adult-like size and shape.

What is the progression of pubic hair development?

Like testicle and penis development, pubic hair development is classified into 5 distinct stages (also called Tanner stages). The pubic hair and other Tanner stages may progress at separate rates.

Tanner stage 1 (preadolescent) - Prior to puberty.  No pubic hair.

Tanner stage 2 (ages 10 to 13)  - Pubic hair begin as fine, sparse, light, straight hairs just above the base of the penis.

Tanner stage 3 (ages 11 to 13.5)  - Pubic hair increases in amount, becomes slightly courser, begins to curl and progresses upward and to the sides of the base of the penis.

Tanner stage 4 (ages 11.5 to 14)  - Pubic hair increases in amount and courseness.  There is still less hair than the typical adult pattern.  There is not yet spread of pubic hair to the thighs.

Tanner stage 5 (ages 13.5 to adult)  -Pubic hair assumes the adult-type pattern with extension of hair onto the inside surface of the thighs.

When does a boy start producing sperm?

Sperm can be found in the testicles prior to puberty, however the first ejaculation occurs shortly after the beginning of puberty.  Ejaculation occurs due to masturbation or spontaneously during sleep.  

Does a boy develop breasts during puberty?

Almost half of boys will have mild breast enlargement during puberty.  It is common for males to have growth of a tender nodule under the nipple (a breast bud) during the early stage of puberty.  Breast enlargement typically resolves completely within a few months.

What are other changes of puberty?

Growth spurt - Adolescent males often have a rapid gain in weight and height during puberty.  The most rapid changes typically occur around the time of the development of armpit hair and begin to slow afterward.

Acne - Most often affects the face, neck, back and chest.

Underarm hair - Typically develops at the same rate as pubic hair.

Facial hair -  Typically begins late in puberty with fine hairs above the lip.

Underarm perspiration and body odor -This is due to hormonal changes that stimulate the activity of sebaceous and sweat glands in the skin.

Internal changes - The seminiferous tubules, epididymis, seminal vesicles, and prostate grow in size.

Voice changes - The voice grows deeper late in puberty.  The transition of the voice often takes several months and this may lead to changes in voice tone mid-sentence (voice "cracking"). 

Nocturnal emissions - Ejaculation may occur spontaneously at night with or without a sexually-arousing dream (a.k.a. - "wet dream".

Penile erections - Penile erections occur spontaneously nightly during sleep and at random times during the day.

Emotional changes - Puberty is often a time of emotional lability in adolescents.  This may be due, at least in part to questions of self image, morality, sexuality, conformity and independence which peak during puberty.

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