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Semester 3 repro > Sexual Differentiation and Disorders > Flashcards

Sexual Differentiation and Disorders Flashcards

1
Q

What is the definition of sexual determination?

A

→ Genetically controlled process dependent on the switch on the Y chromosome

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2
Q

What is sexual differentiation?

A

→ The process by which internal and external genitalia develop as male or female

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3
Q

What does gender depend on?

A

→ A switch gene in the Y chromosome

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4
Q

What is genotypic sex?

A

→ XY

→ XX

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5
Q

What is gonadal sex?

A

→ Testes

→ Ovaries

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6
Q

What is phenotypic sex?

A

→ outward appearance

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7
Q

What is Legal sex?

A

→ Passport/birth certificate

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8
Q

What is gender identity?

A

→ How you feel / not always the same as phenotypic

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9
Q

What is the first event that occurs that determines sex?

A

→ Genetic signal which then form testes or ovaries

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10
Q

What gene creates the testes?

A

→ The SRY gene

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11
Q

In the absence of the Y chromosome what develops?

A

→ Ovaries

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12
Q

What does SRY mean?

A

→ Sex determining region

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13
Q

When does the SRY region switch on and what happens when it is switched on?

A

→ During embryo development in > week 7

→ makes gonad into testis

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14
Q

What two types of cells are in the testis?

A

→ Sertoli cells

→ Leydig cells

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15
Q

What do Sertoli cells make?

A

→ Produce anti mullerian hormone

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16
Q

What do Leydig cells make?

A

→ Testosterone

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17
Q

What is SRY?

A

→ A transcription factor that causes self transcription

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18
Q

What happens after fertilization (gonads)?

A

→ A pair of gonads develop which are bipotential

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19
Q

What is the precursor of gonads derived from?

A

→ Somatic common mesenchymal tissue precursors called genital ridge primordia

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20
Q

What do the genital ridges become?

A

→ Ovaries or testes

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21
Q

What does the Mullerian duct become?

A

→ Uterus
→ Uterine tubes
→ Upper third of vagina

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22
Q

What does the Wolffian duct become?

A

→ Vas deferens

→ Prostate

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23
Q

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

A

→ Primordial germ cells
→ Primitive sex cords
→ Mesonephric cells

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24
Q

What do primordial germ cells become?

A

→ Sperm or oocytes

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25
What do primitive sex cords become?
→ Sertoli cells | → or Granulosa cells
26
What do mesonephric cells become?
→ Leydig cells | → Theca cells
27
Describe primordial germ cell migration
→ Small clusters of PGC cells in the epithelium of the yolk sac expand at 3 weeks → Migrate to the connective tissue of the hindgut to the region of the developing kidney and onto the genital ridge
28
Describe what happens to primitive sex cords in the male
→SRY expression →Penetrate the medullary mesenchyme and surround the primordial germ cells to form testis cords →Eventually become sertoli cells which express anti Mullerian hormone
29
Describe what happens to primitive sex cords in the female
→No SRY expression →Sex cords are ill defined and do not penetrate deeply but instead condense in the cortex as small clusters around PGCs →become granulosa cells
30
What type of structures do the sex cords form?
→ Tubular structures with germ cells inside of them
31
Where do mesonephric cells originate from?
→ Mesonephric primordium which are lateral to the genital ridges
32
What do mesonephric cells in males act under the influence of?
→ Pre sertoli cells that are already there and express SRY
33
What do mesonephric cells form in males?
→ Leydig cells - synthesize testosterone → Basement membrane → Vascular tissue
34
What does the basement membrane form in males?
→ Seminiferous tubules and rete-testis
35
What do mesonephric cells form in females?
→ Theca cells | → Vascular tissue
36
What do Leydig cells synthesize?
→ Testosterone
37
What do Theca cells synthesize?
→ Androstenedione which is a substrate for estradiol production
38
What hormone does the male gonad produce that the female gonad does not?
→ Anti mullerian hormone
39
What do Sertoli cells make and what does this do to the Leydig cells?
→ Anti mullerian hormone | → causes Leydig cells to synthesize testosterone
40
Give a summary of the 3 types of cells in males and what they produce?
Primary germ → Sperm cells Primitive sex cords → Sertoli cells (AMH, SRY) Mesonephric cells → Leydig cells (testosterone)
41
Give a summary of the 3 types of cells in females and what they produce?
Primitive germ → oocytes Primitive sex cords → Granulosa cells (Estradiol) Mesonephric cells → Theca cells (androstenedione)
42
What are Mullerian ducts inhibited by?
→ AMH
43
What are wolffian ducts stimulated by and why do they regress?
→ Regress if there is lack of stimulation by testosterone | → Stimulated by testosterone
44
Where is testosterone converted?
→ Genital skin
45
What is testosterone converted into?
→ dihydrotestosterone
46
What enzyme is used to convert testosterone?
→ 5areductase
47
What form of testosterone is more potent?
→ dihydrotestosterone
48
Describe how DHT cause differentiation of male external genitalia
→ Clitoral area enlarges into penis → Labia fuse and become rugated to form scrotum → Prostate forms
49
Why is there no differentiation of female genitalia into male genitalia if 5a reductase is present?
→ there is no substrate (testosterone)
50
Flowchart of sequence leading to differentiation of external male genitalia
``` SRY is expressed with a Y chromosome ↓ Sertoli cells form ↓ Testis formation occur ↓ Sertoli cells secrete AMH ↓ Regression of Mullerian duct ↓ Leydig cells secrete testosterone ↓ Growth of Wolffian duct ↓ Testosterone is acted on by 5 a reductase to DHT ↓ development of male external genitalia ```
51
Flowchart of sequence leading to differentiation of external female genitalia
``` no Y chromosome ↓ no AMH ↓ Mullerian ducts grow ↓ Ovary doesn't produce testosterone ↓ Wolffian ducts regress ↓ External female genitalia develop ```
52
What is gonadal dygenesis?
→ Sexual differentiation is incomplete | → Missing SRY in male or partial or complete deletion of X in female
53
What is sex reversal?
→ Phenotype does not match genotype | → may be male genotypically but externally female
54
What is intersex?
→ have some components of both tracts or ambiguous genitalia → Sex of infant is difficult to determine
55
What is androgen insensitivity syndrome?
→ XY individual making testosterone but it has no effect
56
What is a clue to androgen insensitivity?
→ lack of body hair | → Amenorrhoea
57
What occurs in a 5 alpha reductase deficiency?
→ Testes form and AMH acts → Internal structures form → External structures do not develop → Appear mainly female
58
What is turner syndrome?
→ When there is the absence of an X chromosome
59
What are the characteristics of turner syndrome?
→ Streak ovaries | → ovarian dysgenesis
60
How does congenital adrenal hyperplasia work?
→ when an XX female is exposed to high levels of androgens in utero
61
What does the adrenal gland make?
→ Steroids
62
What are the main steroids that the adrenal gland makes?
→ Aldosterone and cortisol
63
Where are the rest of the steroids made and what are they called?
→ In the gonads → Testosterone → progesterone → Estrogen
64
What is the structure of cholesterol?
→ 3 six sided rings | → one 5 sided ring
65
What is the difference between the estrogens?
→ THe number of OH groups on them
66
What happens if 21 hydroxylase doesn't work?
→ Cortisol not produced → More ACTH produced (negative feedback) → ACTH causes cholesterol to be taken up → Cholesterol is converted into androgens instead
67
What happens to girls when 21 hydroxylase doesn't work in utero?
→ Increase in testosterone → Growth of wolffian duct → External genitalia are male
68
What is the treatment for 21 hydroxylase deficiency?
→ Glucocorticoid
69
Describe how estrogens are made
→Cholesterol is imported into the cell and has the carbons from carbon 21-27 cleaved → it becomes prenenolone (progestagens) which has 21 carbons and two carbons are removed → this makes androgens which have 19 carbons and another carbon is removed →this forms estrogens which have 18 carbons
70
What does 21 hydroxylase do?
→ Convert cholesterol into cortisol and aldosterone

Semester 3 repro (12 decks)

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