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s4 - Repro, Develop, Ageing, Pharm > REPRO - Genetics > Flashcards

REPRO - Genetics Flashcards

1
Q

What does SRY transcription factor gene code for? When would it switch on..week.?

A

male pathway -> testes that make AMH & testosterone

week 7

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2
Q

The bipotential gonads are derived from what?

At week..?

A

Common somatic mesenchymal tissue “the genital ridge primordia” around week 3/week 4

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3
Q

What is the duct called that forms the: epididymus, vas deferans, prostate gland and seminal vesicles?

A

Wolffian/mesonephric

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4
Q

What duct forms the uterus, fallopian tubes, cervix and upper 1/3rd of vagina?

A

Mullerian/paramesonephric duct

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5
Q

What are the 3 waves of cells that invade the genital ridge?

A
  • primordial germ cells (PGCs)
  • primitive sex chords
  • mesonephric cells
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6
Q

PGCs begin as cell cluster in yolk sac epithelium than expand by mitosis (wk 3) then migrate to….

A

..CT of the hind gut -> genital ridge (colonised at wk 6)

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7
Q

PGCs form..

A
  • oocytes

- spermatoza

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8
Q

The primitive sex chords are from the germinal epithelium that overlies the genital ridge then migrates.. and in men/women..

A

inwards as columns

  • men: they penetrate the medulary mesenchyme, and surround PGCs forming testis cordis. Become sertoli cells.
  • women: ill defined, dont penetrate, condense in cx as clusters around PGCs. Become granulosa cells.
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9
Q

What do sertoli cells express?

A

AMH (Anti Mullerian Hormone)

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10
Q

Where do mesonephric cells originate?

A

Mesonephric primordium (lat to genital ridge)

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11
Q

Mesonephric cells in men vs women (make vascular tissue in both)?

A

Men: pre-sertoli cells and SRY…leydig cells make testosterone, the basement membrane helps to make semineferous tubules and rete testes
Women: Theca cells make adrostenedione, a substrate for E2 production from granulosa.

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12
Q

If men..what about women:
PCG -> spermatoza
P. sex chords -> sertoli cells (AMH, SRY)
mesonephric cells -> Leydig cells (testosterone)

A

PCG -> oocytes
P. sex chords -> granulosa cells (E2)
mesonephric cells -> Theca cells (androstenedione)

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13
Q

Where is testosterone converted to DHT (dihydrotestosterone) by enzyme…

A

in the genital skin, by 5a reductase

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14
Q

DHT on the testosterone receptor causes differentiation of ext. male genitalia how?

A
  • genital tubercle and urethral fold enlarges into penis

- genital swellings fuse and become ruggated into scrotum

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15
Q

In females (with no DHT) what does the genital tubercle, swellings and urethral fold form?

A
  • tubercle forms clitoris
  • swellings form labia majora and minora
  • urethral fold forms opening of vagina
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16
Q

What is testosterone’s function?

A

-differentiation and growth of Wolffian duct structures (seminal vesicles, vas deferens…)

17
Q

What leads to the female external genitalia development?

A

Lack of androgens

18
Q

What is gonadal dysgenesis? Cause in male/female?

A
  • incomplete sexual differentiation

- missing SRY in males, partial/full deletion of 2nd X in females

19
Q

what is sex reversal?

A

When phenotype doesnt match genotype

20
Q

What is intersex?

A

When components of both tracts are present or ambiguous genitalia

21
Q

Androgen Insensitivity Syndrome (AIS) 1/20,000 is due to androgen receptor issue. What happens is..

A

an XY individual appears female at birth

  • they have SRY (make testis, make AMH)
  • make testosterone & DHT but no receptors so Wolffian duct cant grow/no ext. male genitalia
22
Q

How may AIS present?

A

Primary Amenorrhoea, no body hair, undescended testes..NB they may feel female as brain has been exposed to only female signals

23
Q

Partial AIS has varying degrees of srotal/penile development, may be large clitoris..ambiguous..ajd at puberty..

A

..the large androgen surge can cause the appearence of male genitalia on the “female”

24
Q

5a reductase deficiency is normally A.Recessive condition when testosterone is made but no/little DHT so..
at puberty..

A
  • XY, testis form, AMH, Wolffian ducts grow (int=male)
  • no DHT (no ext male so ext=female/ambiguous)
  • adrenarche testosterone may induce virilisation so “female” gets male ext genitalia
25
Q

Turner;s S. (XO) 1/3000, has 1 X due to maternal ovarian dysfunction. No SRY so no AMH, so wolffian regresses and ext=female but you get..

A
  • “streak ovaries”/dysgenesis as we need both X for correct development
  • small uterus and tubes and defects in growth and development and infertile (unless mosaic)
26
Q

No 21-Hydroxylase means no cortisol and lack of neg feedback causes high CRH and ACTH. ACTH at adrenal cx… this is congenital adrenal hyperplasia

A

..more cholesterol uptake, side chain cleavage by p450s, more glucocorticoid secretions but more androgens as cortisol cant be made

27
Q

CAH is XX exposed to high androgens in utero, the completeness of the block varies, generally:

A

XX, no SRY, no testis, no sertoli, no AMH, ovaries form but CAH leads to more testosterone so wolffian and mullerian duct form (both int) and DHT leads to male ext.

28
Q

Lack of aldosterone in CAH can be lethal by

Whats given to correct feedback in CAH

A

“salt wasting”

-glucocorticoids

29
Q

Steroids are made from cholesterol which has:

  • # carbons
  • # six sided rings
  • # 5 sided ring
  • with a
A
  • # 24 carbons
  • # 3 six sided rings
  • # a 5 sided ring
  • with a tail
30
Q

Steroids are made by cutting off carbons of tail/switching groups

  • # 21 carbons are
  • # 19 carbons are
  • # 18 carbons are
A 
21 = progestogens (e.g. progesterone, pregnenolone)
19 = androgens 
18 = oestrogens
31
Q

What is Justice?

A

Acting in fairness, equal care for all

32
Q

Ethics. Non-maleficence (avoid unneccessary harm), Benefience (best interests), Justice and what?

A

Respect Autonomy - enable people to make their own reasoned informed choice

33
Q

What 3 steps can be taken if you have concerns that a situation is unethical?

A
  • talk to your colleagues
  • document your discussions
  • contact the ethics committee if needed

s4 - Repro, Develop, Ageing, Pharm (14 decks)

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