Sexual Development

Aka: Sexual Development, Puberty, Pubertal Milestone, Puberty Stage, Tanner Staging, Tanner Scale, Pubarche, Thelarche, Adrenarche, Gonadarche

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II. Definitions

  1. Pubarche
    1. First onset of public hair as a result of Estrogens in girls and androgens in boys
    2. Coincides with Tanner Stage 2, and typically with Thelarche in girls
  2. Gonadarche
    1. Marks the onset of Puberty (more evident in boys, as ovarian growth is not readily evident)
    2. GnRH released (activating the hypothalamic-pituitary-gonadal axis)
    3. Boys
      1. Testicles grow in size
      2. LH stimulates Testosterone production
      3. FSH stimulates sperm maturation
    4. Girls
      1. Ovaries grow in size
      2. FSH stimulates Estrogen and follicle formation
      3. LH stimulates corpus luteum after Ovulation
  3. Thelarche
    1. Onset of secondary Breast development (marks the observable start of Puberty in girls)
    2. Breast buds palpable and areolae enlarge
    3. Peaks at ages 10.2 to 11.3 years, and precedes Menarche by 24 months
    4. Coincides with Tanner Stage 2
  4. Adrenarche
    1. Increased weak adrenal androgen secretion (DHEA, Androstenedione)
    2. Primarily related to adrenal maturation
      1. Contrast with Gonadarche which is more specific to Sexual Development
    3. Peaks between ages 10-14 years
    4. Coincides with Tanner Stage 3 and 4
    5. Transient growth spurt
    6. Axillary and pubic Hair Growth (beyond the minimal pubic hair present in Tanner Stage 2)
    7. Skin oiliness develops (mild acne may form)
    8. Body odor starts

III. Exam: Normal Development

  1. Normal Physiologic Pathways
    1. Central Pathways
      1. Hypothalamus produces Gonadotropin Releasing Hormone (GnRH)
      2. GnRH stimulates anterior pituitary Hormone release
        1. Luteinizing Hormone (LH)
        2. Follicle Stimulating Hormone (FSH)
    2. Peripheral Pathways
      1. Female
        1. FSH triggers ovarian follicles to release Estradiol
        2. LH triggers Ovulation with corpus luteum release of Progesterone
      2. Male
        1. FSH triggers spermatogenesis by Sertoli cells in the Testes
        2. LH triggers Testosterone release from the Leydig cells
    3. Images
      1. hypothalamusPituitaryHormones.png
  2. Characteristic Changes
    1. Male Tanner Stage
    2. Female Tanner Stage

IV. Exam: Abnormal Development

  1. Precocious Puberty
    1. Secondary sexual characteristics before age 8 years in girls, and before age 9 years in boys
    2. Significant abnormalities more frequently affect boys
    3. Central Precocious Puberty
      1. Early activation of Hypothalamus or pituitary release of FSH and LH
    4. Peripheral Precocious Puberty
      1. Early gonad activation
      2. Early sex Hormone release (e.g. Testosterone, Estradiol)
      3. Exogenous Hormone exposure (e.g. Testosterone gel, Estrogen Creams)
      4. Endocrine disrupting chemical exposures (e.g. Pesticides, BPA, phthalates, flame retardants)
  2. Delayed Puberty
    1. No signs of Breast development by age 13 years, or Menarche by age 15 years in girls
    2. No signs of testicular enlargement by age 14 years in boys

V. References

  1. Brown (2025) Am Fam Physician 112(5): 513-21 [PubMed]
  2. Klein (2017) Am Fam Physician 96(9): 590-99 [PubMed]

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