Puberty Physiology

Question 1

Puberty

Answer 1

final stage of maturation of hypothalamo-pituitary-gonadal axis culminating in adult phenotype
- secondary sex characteristics appear and growth spurt occurs, which results in sexual dimorphism to mature, fertile adults

Question 2

Neonatal to Puberty Axis Stages

Answer 2

1. Mini-puberty of infancy -> axis is biologically active
   - sex steroid levels comparable to those in puberty, no peripheral effects (relevance unknown)
2. Long Period of pre-puberty state of HPG suppression
3. Children enter puberty when suppression released -> activation of HPG axis

Question 3

Puberty

Answer 3

1. increase in activity of adrenal gland (steroids)
2. increase in pulsatile GnRH and FSH/LH secretion
3. Increased in estrogen (females) and testosterone (male)
4. Mitosis of primary spermatogonia (no/little mitosis of oogonia)
5. Correlated onset of gamete maturation

Question 4

Pubertal diurnal and pulsatile secretion of GnRH and LH

Answer 4

does not require presence of gonads

Question 5

Normal phenotypic changes during puberty

Answer 5

Axial Growth
Growth of sex organs
Gender specific hair growth
Central processing alterations due to remodeling
Vocal Cord thickening
Menarche
Libido

Question 6

Tanner Staging

Answer 6

Adrenarche (pubarche) - pubic hair growth
Thelarche (breast development due to estrogen)
Gonadarche (production of ovarian hormones and mature gametes)
Menarche (uterine responses to ovarian hormones)

Question 7

Normal age for puberty

Answer 7

Depends of genetics, nutrition, body weight, fat mass

Question 8

Precocious puberty

Answer 8

when puberty appears too early

1. Gonadotropin dependent precocious puberty
   - 80% idiopathic, 20% CNS related
2. Gonadotropin independent precocious puberty
   - Girls = ovarian cysts/tumors
   - Boys = leydig tumors, germ cell tumors
   - Both - exogenous estrogen, pituitary tumors

Question 9

GDPP

Answer 9

early activation of pulsatile activity of gonadotropin axis -> all puberty signs are stage matched but occur earlier than expected

• pulsatile GnRH
• increased LH and FSH
• increased steroid output

Question 10

GIPP

Answer 10

1 or 2 signs of puberty are exhibited but others are dissimiliar

• congenital adrenal hyperplasia
• display of bone age older than chronological age

Question 11

Precocious puberty and growth

Answer 11

prepubertal bone plates are sensitive to estradiol E2

• children are shorter than average
• estrogen has biphasic effect on epiphyseal growth
  a) low levels of E2 favor pubertal growth
  b) high levels cause fusion of epiphyses

Question 12

Diagnosis of GDPP

Answer 12

GnRH analog stimulation test
- gonadotropin levels induced by GnRH stim = GDPP
- gonadotropin levels not induced by GnRH = GIPP
Random LH screening
- 0.1 is prepubertal
- 0.3 or more is pubertal

Question 13

Treatment of GDPP

Answer 13

medical castration drugs

• GnRH agonists (nonpulsatile) or antagonists
• Anti-estrogen/anti-androgens

Question 14

Sexual Dimorphism and Ambiguity

Answer 14

Dimorphism - sex chromo make-up, gonad differentiation, phenotypic manifestation
Ambiguity - mutations in hormone production, receptors, or signaling
- hypogonadism, sex chromo loss, mosaic individuals

Question 15

Development of Internal Sex Organs

Answer 15

At 6 weeks of fetal development

• Gonadal cortex becomes ovary in ABSENCE of SRY protein -> no testosterone -> Wolffian duct degenerates -> Mullerian duct becomes fallopian tube
• Gonadal cortex becomes testis in PRESENCE of SRY protein -> anti-Mullerian hormone causes Mullerian duct to degenerate -> testosterone -> Wolffian duct into vas, epididymis

Question 16

Causes of Sexual Ambiguity

Answer 16

Congenital Adrenal Hyperplasia
Androgen insensitivity syndrome
5-alpha reductase deficiency

Question 17

Congenital Adrenal Hyperplasia

Answer 17

21 hydroxylase deficiency -> excess androgens

• virilization of XX female -> gential ambiguity
• not exposed to anti-mullerian hormone so they form normal -> however high androgens cause them to become ambiguis

Question 18

Androgen Insensitivity Syndrome

Answer 18

mutations in androgen receptors that reduce AR signaling (X-linked)

• inguinal or labial testes -> androgens produced
• both Wolffian and Mullerian ducts regressed

Question 19

5alpha reductase deficiency

Answer 19

XY have symptoms, XX do not

- testosterone is produced, but DHT is not

Question 20

Turner Syndrome

Answer 20

XO (females only) -> sex chromosomes are doled out unevenly between dividing cells (the earlier in development, the more extreme the mosaicism)
- no breast development

Question 21

Kleinfelter syndrome

Answer 21

XXY -> so SRY protein is produced and some testicular development occurs
- small testis at puberty and reduced fertility