Development of secondary sexual characteristics
- Initiation
- Pulsatile release of GnRH (Hypothalamus) → stimulates Anterior Pituitary.
- Anterior Pituitary releases LH and FSH.
- Adrenarche (↑ adrenal androgens, ~ages 6-8) precedes gonadarche but is a separate process.
- Female Sequence (Overall: ages 8-13).
- 1. Thelarche (Breast Budding): First sign, driven by estrogen.
- 2. Pubarche (Pubic Hair): Driven by adrenal and gonadal androgens.
- 3. Menarche: First menstrual period; occurs ~2-3 years after thelarche (average age 12.5).
- Male Sequence (Overall: ages 9-14).
- 1. Gonadarche (Testicular Enlargement ≥ 4 mL or 2.5 cm): First sign, driven by testosterone.
- 2. Pubarche & Penile Growth: Follows testicular enlargement.
- 3. Spermarche: First ejaculation, typically occurs during genital Tanner Stage 4.
- Tanner Staging (SMR) with Typical Ages
- Stage 1 (Prepubertal): No secondary sexual characteristics. (< 8-9 yrs).
- Stage 2 (Female: 8-13 yrs | Male: 9-14 yrs):
- (F): Breast budding (thelarche) & sparse pubic hair on labia.
- (M): Testicular/scrotal enlargement & sparse pubic hair at base of penis.
- Stage 3 (Female: ~10-14 yrs | Male: ~11-15 yrs):
- (F): Breast and areola enlarge; pubic hair darkens and coarsens. Peak height velocity occurs.
- (M): Penis lengthens; testes enlarge further. Pubic hair darkens/coarsens. Voice may begin to change. Peak height velocity occurs.
- Stage 4 (Female: ~10-15 yrs | Male: ~12-16 yrs):
- (F): Areola and papilla form a secondary mound. Pubic hair is adult-type but covers a smaller area. Menarche typically occurs.
- (M): Penis grows in length and circumference; testes/scrotum darken. Pubic hair is adult-type. Spermarche typically occurs.
- Stage 5 (Female: ~13-16 yrs | Male: ~14-18+ yrs):
- (F): Adult breast contour (areola recedes). Adult pubic hair quantity and distribution. Growth slows/stops.
- (M): Adult genitalia size. Adult pubic hair. Facial hair present. Growth slows/stops.