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FHB Exam 4: Endocrinology and Reproduction > Reproduction I: Sexual Determination & DSDs > Flashcards

Reproduction I: Sexual Determination & DSDs Flashcards

1
Q

What is the hierarchy of determinants of sexual differentiation?

A

chromosome -> gonads -> genitalia -> gender identity

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2
Q

Where is the SRY gene located?

A

on the short arm (p arm) of the Y chromosome

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3
Q

What is the target of SRY?

A

SOX9 (drives development of testes)

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4
Q

What do Sertoli cells do?

A

secrete antimullerian hormone and help developing sperm mature (“nurse cells”)

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5
Q

What do Leydig cells do?

A

synthesize and secrete androgens (testosterone, which can be metabolized to DHT and E2)

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6
Q

Primordial germ cells (PGC) migrate to gonadal ridge at which part of gestation?

A

5-6 weeks

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7
Q

What leads to gonad differentiation in males vs. females?

A

specific gene expression patterns

males: Sry + Sox9
females: Rspo1 + Wnt4

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8
Q

What are the 3 main cell types in testes?

A

gametes (sperm), Sertoli cells, Leydig cells

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9
Q

What are the main cells types in the ovaries?

A

gametes (ova) and follicular cells; follicular maturation results in formation of granulosa cells and thecal cells

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10
Q

Which part of the primordial gonad develops into female internal genitalia, and which part develops into male internal genitalia?

A
  • cortex: female

- medulla: male

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11
Q

Which cells in the ovaries are responsible for secreting and synthesizing estrogens and progesterone?

A

granulosa cells

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12
Q

What is another name for the Mullerian duct and Wolffian duct, respectively?

A
  • Mullerian=paramesonephric duct

- Wolffian=mesonephric duct

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13
Q

What induces the regression of the Wolffian duct?

A

absence of testes (NOT presence of ovary); absence of testes=no AMH or androgens

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14
Q

What induces the regression of the Mullerian duct?

A

Sertoli cells make AMH and inhibit B, which induce regression of the Mullerian duct

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15
Q

What is responsible for stimulating formation of internal genitalia from Wolffian duct?

A

testosterone and DHT from Leydig cells

T=epididymis, ductus deferens, seminal vesicle, ejaculatory duct; DHT=prostate, external genitalia

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16
Q

What is the relationship between testosterone and DHT?

A

testosterone is converted to DHT via 5-alpha reductase

17
Q

What is responsible for male pattern baldness?

A

DHT levels that are too high

18
Q

Which male structures require DHT?

A

penis, scrotum, prostate

19
Q

Why are few oogonia present at birth?

A

they are all converted to primary oocytes or subject to atresia

20
Q

What causes arrest of primary oocyte in the diplotene stage?

A

oocyte maturation inhibitor (OMI)

21
Q

What is chimerism?

A

condition where a person has 2 complete genomes (sets of DNA) in their body; in other words, the person is composed of cells with distinct genotypes (arising from different zygotes)

22
Q

What is mosaicism?

A

cell-specific chromosome differences, or 2+ populations of cells with different genotypes in an individual who developed from a single fertilized egg (ex: X-inactivation, where the X chromosome from mom works in some cells, while the X chromosome from dad works in others)

23
Q

How can an XX genotype have a male phenotype, or a XY genotype have a female phenotype?

A

due to chromosomal translocation, where the SRY gene either can translocate to the X chromosome (XX genotype w/ male phenotype) and/or be deleted from the Y chromosome (XY genotype w/ female phenotype)

24
Q

Explain Turner’s Syndrome.

A
  • 45, XO karyotype
  • Since both X chromosomes are required during development for oogonia, ovary becomes a “streak”
  • Systemic phenotypic issues due to aneuploidy
  • Short in stature, no menstruation, no breasts
25
Q

Explain Klinefelter’s Syndrome.

A
  • 47, XXY karyotype
  • Testes present due to Y chromosome, but they are small
  • Infertile
  • Low testosterone w/ micropenis
  • Eunuchnoid body
  • Gynecomastia due to elevated estradiol
  • Systemic phenotypic issues due to aneuploidy
26
Q

Explain what happens with XY, loss of X-linked gene for androgen receptor.

A
  • Pseudohermaphrotidism (no external genitalia)
  • No Mullerian or Wolffian duct
  • No response to androgens
27
Q

Explain what happens with XY, loss of 5alpha-reductase gene.

A
  • Ambiguous genitalia due to inability to make DHT

- No Mullerian duct but Wolffian duct is developed (due to absence of androgens)

28
Q

What is the etiology of hermaphroditism?

A

chromosomal or hormonal; 60% are XX

29
Q

What is male/female designation based on in hermaphroditism?

A

gonad (NOT appearance)

30
Q

What is “true” hermaphroditism?

A

both testes and ovaries are present, and phenotypic sex is ambiguous

31
Q

Explain male pseudohermaphroditism (complete).

A
  • 46, XY
  • Androgen resistance (loss of X-linked AR gene)
  • Androgen levels are high due to lack of negative feedback
  • Estrogen levels are high, inducing development of female body characteristics (phenotype=female w/ blind vaginal pouch)
  • No duct development, so no internal genitalia
32
Q

Explain male pseudohermaphroditism (partial).

A
  • 46, XY
  • Androgen resistance (AR mutation, so partially functional)
  • Androgen levels are high due to lack of negative feedback
  • Estrogen levels are high; phenotype=ambiguous w/ blind vaginal pouch and undermasculinized features
  • Wolffian duct develops due to some androgens being present
  • No internal genitalia
33
Q

Explain female pseudohermaphroditism.

A
  • 46, XX
  • Most common cause=fetal CAH (due to maternal androgen excess from either an adrenal or ovarian tumor, or from progestational drugs)
  • The earlier the exposure to androgens, the more ambiguous the genitalia
  • Exposure at early stages of differentiation: retention of urogenital sinus and labioscrotal fusion (looks like a penis)
  • Exposure later than 12th week: clitoral hypertrophy
  • Virilization due to excess androgens
  • Advanced skeletal age

FHB Exam 4: Endocrinology and Reproduction (14 decks)

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