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MedST IB: Human Reproduction (HR) > 3.0 Sexual Differentiation > Flashcards

3.0 Sexual Differentiation Flashcards

1
Q

Why did evolution favour sex?

A

Recombination and allelic assortment helps to generate variation in populations (allows adaptation)

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2
Q

What determines gonadal sex?

A

Genetic sex

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3
Q

What determines somatic sex?

A

Gonadal sex affects somatic sex<br></br><br></br>This is done through <b>messengers</b><br></br>- Can be paracrine peptide molecules<br></br>- Or endocrine molecules

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4
Q

What is the autosomal number, sex chromosomes and gonads present for the following conditions:<br></br>1) Turner’s syndrome<br></br>2) Female<br></br>3) Superfemale<br></br>4) Male<br></br>5) Klienfelter’s syndrome<br></br>6) Supermale<br></br>7) Triploid (ovaries)<br></br>8) Triploid (testes)<br></br>9) X-Y tanslocation<br></br>10) Deletion of part of Y

A

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5
Q

What is SRY gene?

A

Sex determining region on Y chromosome<br></br>Encodes the SRY protein

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6
Q

What is the structure and mechanism of SRY protein?

A

SRY protein = 223 amino acids long<br></br><br></br>Contains a 79 amino acid <b>HMG box</b><br></br><br></br>HMG box binds to DNA → ↑ <b>SOX-9</b>

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7
Q

What are the steps for fetal sexual differentiation?

A

“<div><img></img></div>”

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8
Q

What do sertoli cells secrete?

A

<b>MIS (mullerian inhibitory substance)</b><br></br><br></br>MIS → ↓ paramesonephric duct (mullerian duct)

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9
Q

What do Leydig cells secrete?

A

<b>Testosterone</b><br></br><br></br>Testosterone → ↑ mesonephric duct

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10
Q

What does the mesonephric duct become?

A

In males → Vas and associated ducts (epididymis and seminal vesicles)<br></br><br></br>In females → regresses

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11
Q

What does the paramesonephric duct become?

A

In males → regresses<br></br><br></br>In females → Fallopian tube, uterus and top of vagina

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12
Q

What 3 hormones, released from testis, act as gonadal-somatic messengers?

A

<b>1) Androgens</b><br></br>- Stimulate development of penis, scrotum, vasa and accessory sex glands<br></br><br></br><b>2) Insulin like hormone 3</b><br></br>- Stimulate contraction of the gubernaculum → descent of testis<br></br><br></br><b>3) MIS</b><br></br>- Regression of paramesonephric duct (mullerian duct)

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13
Q

What is primary hermaphroditism?

A
  • Can be ovary on one side + testes on other (rare)<br></br>- Can be mixed ovarian/testicular tissue in glands (XO/XY mosaicism)
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14
Q

What is secondary hermaphroditism?

A

1) Congenital adrenohyperplasia (CAH)<br></br><br></br>2) Androgen insufficiency syndrome (AIS)<br></br><br></br>3) 5-alpha reductase deficiency (guevodoces)<br></br><br></br>3) Micropenis<br></br><br></br>4) Hypospadias (urethra opens in ventral penis or in vagina)

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15
Q

What is Congenital adrenohyperplasia (CAH)?

A

<b>Caused by deficiency in 21-hydroxylase (21-OHD)</b><br></br>- This is an enzyme needed for cortisol synthesis<br></br><br></br>21-OHD → ↓ cortisol secretion → ↑ ACTH (no -ve feedback)<br></br><br></br>↑ ACTH → ↑ cortisol precursors which are also precursors for androgens<br></br><br></br>This causes ↑ androgen secretion → in utero <b>virilization</b> of female genitalia

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16
Q

What is Androgen insufficiency syndrome (AIS)?

A

<b>Genotype XY</b><br></br><b>Due to mutation in androgen receptor (AR)</b> - 400 identified<br></br><b>Resistance to androgens → female appearance</b> (range of different physical traits)<br></br><b>Normal testis</b> (may not have descended)<br></br><b>Normal androgen production</b><br></br><b>No uterus/fallopian tube/upper vagina</b>

17
Q

What is 5-alpha reductase deficiency (guevodoces)?

A

5-alpha reductase is needed to make dihydrotestosterone<br></br>This condition have deficiency in external genitalia<br></br>XY but minimal virilisation at birth → extreme virilisation at puberty

18
Q

Define Gender identity

A

An internal state of being<br></br><br></br>How people think of themselves and identify in terms of sex (man, woman, boy, girl)<br></br><br></br>Gender identity is a psychological quality <br></br>Consists of more than two categories:<br></br>(Space for those who identify as a third gender, both, or neither)<br></br>Many people feel that they have masculine and feminine aspects of their personalities

19
Q

Define Gender stereotype or role

A

Socially expected attributes of men and women

20
Q

Define Gender role

A

Everything we do that communicates our sex/gender to others

21
Q

By what age is gender identity established?

A

2yrs

22
Q

By what age is gender role established (what age do children know what is expected of them)?

A

2-3yrs

23
Q

By what age do children realise that gender is fixed (gender consistency)?

A

5 yrs<br></br><br></br>It is at this stage that gender policing starts

MedST IB: Human Reproduction (HR) (13 decks)

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