Sexual Differentiation And Endocrine Control Of Puberty

Front 1

In the absence of testosterone, [ Mullerian duct / Wolffian duct ] regresses. What causes the regression of the non-picked duct?

Back 1

in the ABSENCE of testosterone, the Wolffian duct regresses

Regression of Mullerian duct occurs in males when they secrete anti-mullerian hormone (from the testes).

Front 2

What gene directs the gonads to become the testes in internal genitalia sexual differentiation?

Back 2

SRY gene

Front 3

The SRY gene directs gonads to become testes. The testes then secrete two things. What are they and what do they do?

Back 3

Testes secrete Testosterone and anti-mullerian hormone. Testosterone stimulates formation of the vas deferens, seminal vesicles, and epididymis. AMH causes regression of Mullerian ducts.

Front 4

True or False:
AMH, released from the testes, stimulates formation of vas deferens, seminal vesicles, and the epididymis.

Back 4

FALSE!

This is what testosterone, secreted by the testes, does! AMH makes the mullerian ducts regress!

Front 5

Dihydrotestosterone is necessary for the development of male [ external / internal ] genitalia.

Back 5

External genitalia

Front 6

Testosterone is converted to dihydrotestosterone by the action of the enzyme _______________.

Back 6

5-alpha-reductase

Front 7

Testosterone is converted to _______________ by the action of the enzyme 5-alpha-reductase.

Back 7

dihydrotestosterone

Front 8

__________ acts on the external genitalia to cause formation of the scrotum and penis.

Back 8

DHT (dihydrotestosterone)

Front 9

Congenital adrenal hyperplasia (CAH) is the most common cause for this disorder of an overvirilized female 46XX. What are the physical findings? What biochemical test is done?

Back 9

ambiguous genitalia, enlarged clitoris, no palpable testes, uterus present by ultrasound. Diagnose by measuring 17-OHprogesterone.

Front 10

What are the causes of an undervirilized male (46XY)? (4)

Back 10

- 5-alpha reductase deficiency: inability to convert testosterone to DHT thus external genitalia are undervirilized at birth though have male internal structures. Diagnosed by low DHT but normal or high testosterone.
- androgen insensitivity: resistance to androgen due to receptor defect. Complete resistance results in female phenotype that won't come to attention until puberty when they fail to menstruate. Will have breast development but no pubic hair. Internally have testes. Have shortened vagina but no uterus because of AMH produced by testes. Diagnosis by elevated testosterone, LH and FSH. There are multiple degrees of virilization.
- mixed gonadal dysgenesis (45X/45XY): normal testes one side/ streak gonad other side result sin partial virilization of male and ambiguous genitalia
- pure gonadal dysgenesis (46XY): deletion of SRY gene leads to female phenotype at birth. They have gemale phenotype externally and internally but have streak gonads that do not produce estrogen or testosterone. They present with delayed puberty. They will develop pubic hair, in contrast to those with complete androgen insensitivity.

Front 11

What is 5-alpha reductase deficiency?

Back 11

inability to convert testosterone to DHT thus external genitalia are undervirilized at birth though have male internal structures. Diagnosed by low DHT but normal or high testosterone.

Front 12

What is androgen insensitivity?

Back 12

Male undervirilization condition. resistance to androgen due to receptor defect. Complete resistance results in female phenotype that won't come to attention until puberty when they fail to menstruate. Will have breast development but no pubic hair. Internally have testes. Have shortened vagina but no uterus because of AMH produced by testes. Diagnosis by elevated testosterone, LH and FSH. There are multiple degrees of virilization.

Front 13

What is pure gonadal dysgenesis?

Back 13

(46XY): deletion of SRY gene leads to female phenotype at birth. They have female phenotype externally and internally but have streak gonads that do not produce estrogen or testosterone. They present with delayed puberty.

Front 14

An individual with which condition will NOT produce pubic hair?
A. 5-alpha reductase deficiency
B. congenital adrenal hyperplasia
C. androgen insensitivity
D. pure gonadal dysgenesis

Back 14

C. androgen insensitivity

Front 15

What is the normal first sign of puberty
A. for females
B. for males

Back 15

A. females : breast budding (due to estrogens) at ~ 10 y/o
B. males: testicular enlargement is first sign at ~11 y/o

Front 16

True or False:
Leptin, a hormone made by adipocytes, is necessary for normal LH and FSH . Might explain why obese girls start puberty earlier than non-obese girls.

Back 16

TRUE

Front 17

What is the definition of precocious puberty?

Back 17

Sexual maturation beginning before 8 y/o in girls and 9 y/o in boys.

Front 18

Central (true) precocious puberty and peripheral precocious puberty differ in lab tests. Which is where the LH and FSH are suppressed , and estradiol is elevated? Which is where LH and FSH is in pubertal range and estradiol is elevated?

Back 18

LH and FSH are suppressed , and estradiol is elevated: peripheral

LH and FSH is in pubertal range and estradiol is elevated - central

Front 19

What is treatment for puberty-aged girl with Turner Syndrome?

Back 19

Estrogen replacement to induce development of secondary sex characteristics.