What triggers puberty in males and females?

Puberty is the time when you physically become an adult. During puberty, your body goes through lots of changes. And your emotions might feel stronger and more intense. People usually start going through puberty between ages 8 and 14. Females often start puberty before males do.

Puberty doesn’t happen all at once — it comes in stages and takes many years. You might have some signs of puberty at an early age, while other changes show up years later. Bodies are unique, so puberty is different for each person. Everyone goes through puberty at their own pace.

Puberty is a normal part of life. But it’s still common to feel anxious, excited, and confused about it. Knowing what to expect can make puberty changes seem less weird or stressful. And talking to your parents or other adults you trust also helps. After all, they’ve gone through puberty too. So they probably understand how you feel, and have good advice.

What happens to my body during puberty?

There’s no way around it — your body’s gonna change a lot during puberty. Here’s what to expect.

All bodies:

• You may get acne (AKA zits or pimples) on your face and body. If pimples are stressing you out or causing problems in your life, talk to a doctor.

• You start to sweat more, and you may have body odor (when your sweat smells bad). You may want to shower more and start using deodorant.

• Hair grows under your armpits.

• Hair grows around your genitals — this is called pubic hair.

• You may grow more hair on your arms and legs, and the hair may get darker.

• You may feel some pain in your arms and legs as you grow (AKA “growing pains”)

Males:

• Your voice gets lower or deeper. It may crack sometimes while it’s changing, but that’s totally normal and eventually goes away. Your Adam’s apple (bump in your throat) might get bigger and more visible as this happens.

• Your penis and testicles get bigger.

• Hair may grow on your face, chest, and back.

• Your chest and shoulders get broader.

• You may have swelling around your nipples during puberty. This can look like the start of breasts,  but it usually goes away. This happens to about half of males, and it can last for a few months or up to a few years.

Females:

• Your breasts develop and get bigger.

• Your hips get wider and your body may become more curvy.

• You start getting your period.

• Your labia may change color and grow bigger.

Puberty and your feelings

Puberty is controlled by hormones, and these hormones affect your feelings as well as your body. During puberty, your emotions may become stronger and more intense. It’s common to go through mood swings — when your feelings change quickly and randomly.

During puberty, you’ll probably start having more sexual thoughts and urges. You may feel attracted to males, females, or both — this is sometimes called having a crush. And you might notice that you’re sexually excited (AKA horny or turned on) a lot. As you get older, these feelings probably won't be as strong. Some people masturbate to release this sexual tension and explore their sexuality. Others wait for the feelings to pass. Either way is totally normal.

Puberty can be a very confusing time in your life. Your emotions may seem like they’re out of control. One minute you feel on top of the world, and the next minute you’re down in the dumps. Feeling this way is hard, but you don’t have to go through it alone. Talking with adults you trust may help you sort out your feelings. Parents, grandparents, aunts, uncles, cousins, brothers, sisters, teachers, and counselors can comfort and support you. You can also talk with someone at your local Planned Parenthood health center.

Finding activities that are fun and healthy can help you deal with stress and your feelings, and release extra energy. Physical activity, writing, music, art, or talking with friends are great ways to express your emotions and feel good about yourself.

Puberty is the term used to describe the developmental changes a child undergoes to become sexually mature and physiologically ready for reproduction. It normally begins between the ages of 8-14 in females, and between the ages of 10-16 in males.

In this article, we will discuss the hormonal and physical changes that occur during puberty in boys and girls and its clinical relevance.

Hormonal Changes

Puberty and the reproductive system are controlled by the hormones of the Hypothalamic-Pituitary-Gonadal (HPG) axis. The hypothalamus releases Gonadotropin Releasing Hormone (GnRH) in a pulsatile manner, which stimulates the release of Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from the anterior pituitary gland.

FSH and LH act on the gonads (ovaries/testicles) to stimulate the synthesis and release of the sex steroid hormones (oestrogen/progesterone and testosterone) and support gametogenesis. These sex steroids exert many effects on the reproductive system and feedback negatively on the hypothalamus and the pituitary gland to ensure that circulating levels remain stable.

During childhood the levels of FSH and LH in the body are low. This is thought to be due to the slow cycling of the GnRH pulse generator in the hypothalamus. Approximately a year before the first physical changes of puberty there is a rise in the pulsatile release of FSH and LH, as a result of the GnRH pulse generator being released from CNS inhibition.

The rise in FSH stimulates an increase in oestrogen synthesis and oogenesis in females and the onset of sperm production in males. The rise in LH stimulates an increase in production of progesterone in females and an increase in testosterone production in males. As a result of these hormonal changes the physical changes associated with puberty begin to develop.

The speed of development varies greatly between children, as genetic factors contribute. It is also suggested that body weight influences the onset of puberty.

Physical Changes

Puberty in Females

Thelarche

The first sign of puberty in girls is the beginning of breast development (thelarche). This typically occurs at around age 9-10. Breast buds appear as small mounds with the breast and papilla elevated. Tanner staging is used to assess breast size/development with stages I-V (shown below).

The breasts consist of lobulated glandular tissue embedded in adipose tissue, separated by fibrous connective tissue. Following the clearance of placental oestrogens after birth, the breasts are in a dormant stage until puberty. In this dormant stage there are only lactiferous ducts with no alveoli.

At puberty the increase in ovarian oestrogens causes the development of the lactiferous duct system as the ducts grow in branches with the ends forming the lobular alveoli (small, spheroidal masses). Mediated by progesterone, these lobules will increase in number through puberty.

The breasts continue to increase in size following menarche due to increased fat deposition. Throughout the menstrual cycle, oestrogen and progesterone affect the breast size and composition.

By M•Komorniczak -talk-, polish wikipedist. Illustration by : Michał Komorniczak This file has been released into the Creative Commons 3.0. Attribution-ShareAlike (CC BY-SA 3.0) If you use on your website or in your publication my images (either original or modified), you are requested to give me details: Michał Komorniczak (Poland) or Michal Komorniczak (Poland). For more information, write to my e-mail address: [email protected] [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Figure 1 – Tanner staging in females

Pubarche

The second sign of puberty in girls is typically the growth of hair in the pubic area. The hair initially appears sparse, light and straight; however, throughout the course of puberty it becomes coarser, thicker and darker.

Approximately 2 years after pubarche, hair begins to grow in the axillary area as well. In both sexes, hair growth is a secondary sexual characteristic mediated by testosterone.

Menarche

Menarche is the first menstrual period and marks the beginning of the menstrual cycles. It normally occurs around 1.5-3 years after thelarche and is due to the increase in FSH and LH.

The menarche process typically occurs at ~12.8 years (+/- 1.2 years) for Caucasian girls and 4-8 months later for African-American girls. More information can be found in our menstrual cycle article.

Puberty in Males

Genital changes

The first sign of puberty in boys is the increase in testicular size. The increased LH stimulates testosterone synthesis by Leydig cells and the increased FSH stimulates sperm production by Sertoli cells. Spermatogenic tissue (Leydig cells and Sertoli cells) makes up the majority of the increasing testicular tissue. The progression of testicle size can be measured by tanner staging from stage I to stage V.

As the testicles increase in size the scrotal skin also grows and becomes thinner, darker in colour and starts to hang down from the body. It also starts to become spotted with hair follicles (these appear as little lumps.)

Approximately a year after the testicles begin to grow, boys can experience their first ejaculation because the testicles are now producing sperm as well as testosterone. The first ejaculation marks the theoretical capability of procreation. However, on average fertility is reached one year after first ejaculation.

The growth of the penis follows the testicular enlargement. The penis first grows in length. Then the width of the penis increases as the breadth of the shaft increases. The glans penis and corpus cavernosum also enlarge.

Pubarche

Another pubertal sign in boys is the growth of pubic hair at the base of the penis (pubarche). This often occurs alongside testicular growth. Pubic hairs will initially be light coloured, straight and thin; however, as puberty progresses they become darker, curlier, thicker and more widely distributed. Approximately 2 years following pubarche, hair also begins to grow on the legs, arms, axillae, chest and face.

By M•Komorniczak -talk-, polish wikipedist. Illustration by : Michał Komorniczak This file has been released into the Creative Commons 3.0. Attribution-ShareAlike (CC BY-SA 3.0) If you use on your website or in your publication my images (either original or modified), you are requested to give me details: Michał Komorniczak (Poland) or Michal Komorniczak (Poland). For more information, write to my e-mail address: [email protected] [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Figure 2 – Tanner staging in males

Growth spurt (Males and Females)

The pubertal growth spurt is the product of a complex interaction between the gonadal sex steroids (oestradiol/testosterone), GH and insulin-like growth factor 1 (IGF-1). GH levels will rise in puberty due to the increase in sex steroids (testosterone which has been converted to oestradiol) and their positive effect on the pulsatile release of GH from the anterior pituitary gland.

A rise in GH causes a rise in the anabolic hormone IGF-1, which causes somatic growth via its metabolic actions (e.g. increases trabecular bone growth.)

Following the peak of the growth spurt in males, the larynx and vocal cords (voicebox) enlarge, and the boy’s voice may ‘crack’ occasionally as it deepens in pitch.

Clinical Relevance – Precocious Puberty

We define precocious puberty is as the appearance of secondary sexual characteristics before the age of 8 in girls or before the age of 9 in boys. There are a variety of causes/types:

• Iatrogenic – this occurs as a result of exposure to exogenous oestrogens, e.g. via creams or lotions etc.
• True/complete – due to early maturation of the HPG axis resulting in high levels of GnRH, FSH and LH. This may be due to CNS lesions near or in the posterior hypothalamus, CNS neoplasms, harmatomas, primary hypothyroidism.
• Incomplete – due to increased levels of oestrogens in girls and androgens in boys that are independent of GnRH.

Precocious puberty may either be isosexual (early sexual development consistent with the genetic and gonadal sex of the child) or contrasexual (early sexual development associated with feminisation of a male or virilisation of a female).

Clinical Relevance – Delayed/Absent Puberty

We define delayed or absent puberty as the absence of secondary sexual characteristics by the age of 13 in girls or 16 in boys. There are various causes:

• Hypogondaotropic hypogonadism – this is due to a disorder of either the hypothalamus or the pituitary gland. The disorder results in a deficiency in GnRH, LH or FSH.
• Hypergonadotropic hypogonadism – this is due to a disorder of the gonads (ovaries or testicles.) The disorder results in absent or reduced gonadal steroid secretion which results in high circulating levels of LH and FSH as there is minimal negative feedback from the gonadal steroids on the pituitary gland.
• Clinicians may see multiple conditions associated with delayed puberty. Be careful to watch out for these in exams:
  • Turner’s Syndrome (45 XO)
  • Klinefelter’s Syndrome (47 XXY)
  • Androgen Insensitivity Syndrome
  • Kallmann Syndrome
• When investigating infertility, consider other conditions that are not congenital.

Doctors can treat severe delayed/absent puberty with carefully controlled hormonal replacement therapy.

What triggers the puberty in males?

What causes puberty in females?

What are the 3 main hormones in puberty?