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Puberty

  • Period when the gametogenic and endocrine functions of the gonads have first developed to the point where reproduction is possible
  • Gonads = testes, ovaries
  • Dual function:
    • Production of germ cells (ova, spermatozoa)
    • Secretion of sex hormones ( estrogens, androgens)
  • These functions depend on the secretion of gonadotropins from the anterior pituitary

Males

  • Castration results in a rise in pituitary content and secretion of LH and FSH (no negative feedback)
  • Continuous GnRH suppresses gonadotropin

Females

  • Amount of gondatropin released depends on time of cycle

Sex Hormones in Foetal Life and Infancy

  • GnRH present at 15weeks
  • HP axis functional at 23 weeks
  • Surge in LH and FSH occurs in utero and also post-natally

Sex Hormones in Childhood

  • Release of GnRH is inhibited
  • Low levels of sex steroids
  • Pubertal development can be divided into 5 stages (Tanner’s stages)
    • Girls
      • Thelarche
        • Development of breasts
      • Pubarche
        • Development of axillary and pubic hair
      • Menarche
        • First period
      • Oestrogens cause thickening of vaginal mucosa, enlargement of uterus and cervix (endometrial hypertrophy)
    • Boys
      • Testes enlarge
      • Androgenic effects of testosterone
      • Penis enlargement
      • Scrotum, prostate, seminal vesicles enlarge
      • Pubic and axillary hair development
      • Spermarchy

Male Puberty

  • External genitalia
  • Internal genitalia
    • Seminal vesicles enlarge
  • Voice
    • Larynx enlarges
  • Body
    • Shoulders broaden
    • Muscles enlarge
  • Hair
    • Facial, pubic, chest, axillary, anal
  • Skin
    • Sebaceous secretions thicken (predisposes to acne)
  • Mental
    • Aggression, sexual

Adrenarchy

  • Onset of increased secretion of adrenal androgens
  • Occurs earlier in girls
  • Caused by increased activity of 17alpha hydroxylase
    • Leads to the increased formation of 17alpha hydroyprogesterone from pregneolone and progesterone

Growth Spurt

  • Caused by estrogens and androgens and GH
  • Stops due to closure of epiphyseal plates by oestrogen

Timing of Puberty

  • Genetic
  • Nutrition
    • Critical weight for puberty

Precocious Puberty

  • Early onset of puberty
  • Causes:
    • Hypothalamic disease
    • Tumour, infection
    • Increases release of GnRH
    • Gonadotropin independent
      • Occurs without gonadotropin release increase
      • Eg. increased sensitivity of receptors to LH

Precocious Pseudopuberty

  • Early development of secondary sexual characteristics
  • Occurs due to abnormal early exposure to androgens/oestrogens
    • Can be congenital adrenal hyperplasia, adrenal tumours

Delayed/absent Puberty

  • Lack of thelarche by 13 or menarche by 16
  • Lack of testes enlargement by 14
  • Eg.
    • Panhypopituitarism
    • Turner’s Syndrome