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FHB Hormone/Repro > 82 - Sexual Differentiation > Flashcards

82 - Sexual Differentiation Flashcards

1
Q

How is “sex” determined?

A

Biologically - genotypic or c’somal

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2
Q

How is “gender” determined?

A

Socially-determined (usually related to appearance)

- Independent of genotype, hormones, and phenotype

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3
Q

Describe the “hierarchy” of sexual development.

A

Chromosome determines gonads, determines genitalia, determines gender identity

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4
Q

How would you confirm someone’s biological sex?

A

Karyotype analysis

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5
Q

Generally, what is gonadal development determined by?

A

Genes only (c’somes)

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6
Q

Generally, is genitalia development determined by genes, internal/external structures, environment, hormones, social behavior, or a combo of them?

A
  • Hormones
  • Internal and external structures
  • Social behavior
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7
Q

What c’some is required for testicular development?

A

Y c’some (“Y defines the guy”)

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8
Q

What important gene is found on the Y c’some in the region that determines sex?
What’s its other name?

A
  • SRY: sex-determining region Y

- AKA TDF: testes-determining factor

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9
Q

SRY is a TS factor, it’s major target being:

A

SOX9

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10
Q

What specifically determines gonadal sex?

A

(C’somes)

Determined by normal differentiation and especially activation of SRY/TDF gene to yield male vs female

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11
Q

What what week in pregnancy is the gonad male?

When is it female?

A
  • Male by 7 weeks

- Female by 11 weeks

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12
Q

Although you can determine c’some sex by genomic (karyotype) analysis, what’s the only way you can determine gonadal sex?

A

Histology of the gonad (ouch)

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13
Q

What specifically determines the genitalia?

A

(gonadal sex)
Determined by activation and integration of:
- Neuroendocrine axis
- Paracrine, endocrine control of genital tract devo

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14
Q

How would you determine someone’s gender identification?

A

Observation/psychoanalytical tests

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15
Q

XY mice w/no functional SRY develop ________.

A

Ovaries

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16
Q

XX mice w/added functional SRY develop ________.

A

Testes

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17
Q

What c’some encodes the androgen receptor?

A

X c’some

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18
Q

What cells migrate to the gonadal ridge at 5-6 weeks gestation?

A

Primordial gene cells (PGCs)

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19
Q

Before gonads become testes or ovaries, what are they known as?

A

Primordial (indifferent) gonad

bipotential for testis or ovary

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20
Q

What 2 genes are responsible for development of the testes from the primordial gonad?

A

+ Sry

+ Sox9

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21
Q

What genes are responsible for development of the ovary from the primordial gonad?

A

Neither, just need the absence of the testes!

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22
Q

Although absence of testes is the deciding factor for the primordial gonad to become an ovary, what 2 genes are responsible for the appropriate differentiation into an ovary?

A

+ Rspo1

+ Wnt4

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23
Q

What part of the embryo (foregut, midgut, or hindgut) do the gonads develop in?

A

Hindgut

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24
Q

What are the 2 areas of the gonadal ridge called?

A

Cortex (anterior) and medulla

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25
Q

Female internal genitalia develop from the ________ of the gonadal ridge.

A

cortex

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26
Q

Male internal genitalia develop from the ________ of the gonadal ridge.

A

Medulla

“m” for male = medulla

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27
Q

Describe the 4 steps of the embryologic development of the male gonad.

A
  1. Indifferent gonad = primitive sex cords
  2. Proliferation of sex cords (SRY, SOX9)
  3. Penetration of medulla by sex cords
  4. Differentiation of medullary cords – becomes testes
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28
Q

Describe the 4 steps of the embryologic development of the female gonad.

A
  1. Indifferent gonad = primitive sex cords
  2. Sex cords disorganize – cortical epithelial cells proliferate (due to absence of SRY)
  3. Cortical cords develop from cortical epithelium
  4. Cells form clusters around germ cells – epithelial cells become follicular cells – ovary develops
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29
Q

What are the 3 types of cells of the testes?

A
  1. Gametes
  2. Sertoli cells
  3. Leydig cells
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30
Q

What are male gametes called?

A

Sperm

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31
Q

What are female gametes called?

A

Ovum

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32
Q

What do Sertoli cells (of the testes) do?

A

Secrete antimullerian hormone (AMH) and inhibin B

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33
Q

What do Leydig cells (of the testes) do?

A

Synthesize and secrete testosterone/DHT (androgens)

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34
Q

What are the 2 cell types of the early ovary?

A
  1. Gametes

2. Follicular cells

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35
Q

Together, the gametes and the follicular cells of the early ovary make up the:

A

Follicle

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36
Q

Follicular maturation results in formation of what 2 cell types w/in the ovary?

A
  1. Granulosa cells

2. Thecal cells

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37
Q

What do granulosa cells (of the mature ovarian follicle) do?

A

Secrete and synthesize estrogens and progesterone

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38
Q

What do thecal cells (of the mature ovarian follicle) do?

A

Make androgens

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39
Q

The germ cells of the male are called ________________, and those of the female are called _______________.

A
  • Spermatogonia

- Oogonia

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40
Q

The coelomic epithelium of the male will become ___________ cells, and that of the female will become _____________ cells.

A
  • Sertoli (secrete AMH, inhibin B)

- Granulosa (secrete estrogens/progesterone)

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41
Q

The mesenchymal cells of the male will become ___________ cells, and that of the female will become _____________ cells.

A
  • Leydig (secrete testosterone/DHT)

- Theca cells (make androgens)

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42
Q

AMH + androgens will result in development of the:

A

Male genital tract/external genitalia

43
Q

No AMH + no androgens will result in development of the:

A

Female genital tract/external genitalia

44
Q

Name the 3 parts of the “sexually indifferent duct system” of the developing fetus.

A
  1. Mesonephros
  2. Mullerian Duct
  3. Wolffian Duct
45
Q

What is the mesonephros and when does it start working?

A

Transient kidney

- 6-10 weeks gestation

46
Q

Which of the 2 sexually indifferent ducts undergoes further development in females?

A

Mullerian duct

recall: males have anti-mullerian hormone

47
Q

Which of the 2 sexually indifferent ducts undergoes further development in males?

A

Wolffian duct

48
Q

What’s another name for the Wolffian duct? Mullerian duct?

A

W: Mesonephronic duct
M: Paramesonephronic duct

49
Q

What does AMH do?

A

Anti-Mullerian hormone induces regression of the Mullerian duct

50
Q

Recall: Leydig cells make/secrete testosterone and DHT (androgens). What, generally, is the purpose of this?

A

Stimulates the formation of genitalia from the Wolffian duct.

51
Q

What 4 specific parts of the male internal/external genitalia does release of testosterone from Leydig cells form?
(top, middle, bottom)

A
  • Top: epididymis
  • Middle: ductus deferens (vas)
  • Base: seminal vesicle, ejaculatory duct
52
Q

What (2) specific parts of the male internal/external genitalia does release of DHT from Leydig cells form?

A

Prostate and external genitalia

53
Q

Recall: what induces the regression of the Wolffian ducts?

A

Absence of Testes (not presence of ovary)

- No AMH, no androgens

54
Q

What do the top, middle, and bottom of the Mullerian ducts differentiate into?

A
  • Top: Fallopian tubes (oviducts)
  • Middle: fuses to become uterus
  • Bottom: Cervix + upper 1/3 vagina
55
Q

When contrasting patterns of male and female differentiation of the internal genital ducts, what duct develops when you castrate the male? Female?

A

Male castration: Mullerian (instead of Wolffian)

Female castration: Still get Mullerian

56
Q

During male castration, why do Mullerian ducts develop instead of Wolffian ducts?

A

Lack of AMH (AMH induces regression of the Mullerian duct)

57
Q

During female castration, why do Mullerian ducts still develop?

A

Because AMH would never be released anyways…further evidence that absence of testes induces regression of the Wolffian ducts

58
Q

In male early castrates + testosterone, what ducts would you expect to develop?

A

Both because no AMH so no regression of the Mullerian duct, + testosterone induces

59
Q

How would you alter the normal female development of her normal internal genitals in order to get both Mullerian and Wolffian ducts?

A
  • Absence of testicles and lack of AMH induces Mullerian ducts.
  • Then just add testosterone to induce presence of the Wolffian ducts as well.
60
Q

The genital tubercle becomes the __________ in the male and the __________ in the female.

A
  • Glans penis

- Clitoris

61
Q

The urogenital folds become the __________ in the male and the __________ in the female.

A
  • Ventral penis

- Labia minora

62
Q

The urogenital sinus becomes the __________ in the male and the __________ in the female.

A
  • Prostate

- Lower vagina

63
Q

The labioscrotal folds become the __________ in the male and the __________ in the female.

A
  • Scrotum

- Labia majora

64
Q

What hormone is converted into DHT?

A

Testosterone

65
Q

What 3 male genital parts things require DHT for their development?

A
  • Penis
  • Scrotum
  • Prostate
66
Q

What enzyme is required to convert testosterone into DHT?

A

5alpha-reductase

67
Q

A mutation in 5alpha-reductase would cause what problems?

A

Defects in external male genitalia (penis, scrotum, prostate)

68
Q

What general class of cells undergoes meiosis?

A

Germ cells

69
Q

What’s another name for gender identity + external genitalia?

A

Phenotypic sex

70
Q

How do daughter cells differ in mitosis?

A

They are identical (somatic cells only)

71
Q

What is accomplished during meiosis I?

A
  • Duplication of DNA.
  • Recombination of chromosomes = genetic diversity.
  • Chromosomes split
72
Q

At the end of meiosis I, what is the ploidy of the cells?

What about after meiosis II?

A
  • 2x diploid

- 4x haploid

73
Q

What are the names of the male and female gametes?

A
  • Male: spermatozoa

- Female: ovum

74
Q

Name the 4 different names for the sperm cells during their meiotic process, and what happens for each to form + the ploidy.

A
  1. Spermatogonium (diploid)
  2. Primary spermatocyte (diploid, after DNA duplicates)
  3. Secondary spermatocyte (haploid, after 1 cell division)
  4. Spermatids (haploid, after 2 cell divisions, half of gamete DNA)
    - Then become spermatozoa
75
Q

Name the 4 different names for the egg cells during their meiotic process, and what happens for each to form + the ploidy.

A
  1. Oogonium (diploid)
  2. Primary oocyte (diploid, after DNA duplicates)
  3. Secondary oocyte + 1 polar body (haploid, after 1 cell division)
  4. Ovum + 3 polar bodies (haploid, after 2 cell divisions, half of gamete DNA)
76
Q

What 2 things are contained in the primordial follicle?

A
  1. 1 daughter cell/germ cell

2. polar bodies

77
Q

What happens to the oogonia before birth?

A

None are present–all have been converted to primary oocytes or are subject to atresia

78
Q

What step is the female meiosis arrested at until puberty?

A

Meiosis I is arrested at diplotene of prophase

79
Q

What compound is responsible for the arrest of female meiosis I at diplotene of prophase until puberty?
What cells secrete it? (think)

A

Oocyte maturation inhibitor (OMI)

- Small peptide secreted by follicular cells

80
Q

Female meiosis __ is arrested at __________ __ until fertilized by sperm.

A

Meiosis II, metaphase II (then completes meiosis)

m2 m2’s are waiting to get pregnant

81
Q

When does male spermatogenesis generally end?

A

“old age”

82
Q

What’s a translocation?

A

Equal or unequal exchange of c’somal material b/w c’somes

83
Q

When a translocation occurs, what is the reason an XX female develop a male phenotype?

A

SRY gene inserted (eg from Y tralocation w/female X)

- X inactivation can cause a variety of presentations

84
Q

How could an XY male develop female genitalia?

A

Translocation of SRY off of Y gene, so no SRY on either.

85
Q

How many c’somes does a normal karyotype have?

A

46

86
Q

In terms of the sex c’some, what is Turner’s syndrome?

A

45 XO

87
Q

In terms of the sex c’some, what is Klinefelter’s syndrome?

A

47 XXY

88
Q

What is Turner syndrome characterized by (in terms of sex devo)?
What other sx characterize Turner’s syndrome?

A

45 XO

  • Gonadal dysgenesis–ovaries don’t develop and become a “streak” of fibrous tissue (both X chromosomes are required during development for oogonia).
  • Systemic issues due to aneuploidy: very short stature, “shield chest,” webbed neck, upper torso deformities, amenorrhea, lack of puberty
89
Q

Although both X chromosomes are required during development for oogonia and early differentiation of the ovary, why are 2 copies of X no longer required later in life?

A

X inactivation (duh)

90
Q

What is Klinefelter’s syndrome characterized by (in terms of sex devo)?
What other sx characterize Turner’s syndrome?

A

47 XXY

  • Testes are present but small and hyalinated; infertile, low T (due to testes disfunction); micropenis
  • Eunuchoid body (lower segment greater than upper); short arms; gynecomastia (elevated estradiol); other issues due to aneuploidy
91
Q

What is usually the cause of Klinefelter’s syndrome?

How common is it?

A
  • Usually due to meiotic nondisjunction

- Most common chromosomal disorder in boys (1:500 to 1:1000)

92
Q

What are the (2) different general etiologies of hermaphroditism?

A

Chromosomal (genetic); Hormonal (development)

93
Q

What distinguishes male pseudohermaphroditism?

A

Testes present, but some or all female internal/external genitalia also present

94
Q

What distinguishes female pseudohermaphroditism?

A

Ovaries present, but some or all male internal/external genitalia also present

95
Q

What distinguishes true hermaphroditism?

A

Both testes and ovaries present “gonadal” sex. Phenotypic sex ambiguous.

96
Q

What is the genotypic number and cause of complete male pseudohermaphroditism?
How is hormonal balance affected?

A

46, XY

  • Loss of X-linked AR gene (androgen resistance gene)
  • Androgen levels are high (lack of feedback, estrogen levels high (for male). Gonadotropins?
97
Q

What is the sexual phenotype of complete male pseudohermaphroditism?
(there are lots of details here, try to name some. What ducts are present?)

A

Phenotype: female with blind vaginal pouch

  • Y chromosome induces mullerian duct regression, testes (undescended); lack of androgen effects (no Wolffian duct development, no external genitalia)
  • High estrogens induce development of female body characteristics
98
Q

What is the cause of partial male pseudohermaphroditism?How is hormonal balance affected?

A

Partial: AR mutation – partially functional

- Same as complete: Androgen levels are high (lack of feedback, estrogen levels high (for male). Gonadotropins?

99
Q

What is the sexual phenotype of partial male pseudohermaphroditism?
(there are lots of details here, try to name some. What ducts are present?)

A
  • Phenotype: ambiguous with blind vaginal pouch (under masculinized)
  • Y chromosome – induces Mullerian duct regression, testes (undescended); Wolffian duct develops, gynecomastia
100
Q

What are the (4) most common causes of female pseudohermaphroditism?

A
  • Fetal congenital adrenal hyperplasia (most common)
  • Maternal androgen excess
  • Adrenal or ovarian tumors
  • Progestational drugs (eg BCP while pregnant)
101
Q

What is the phenotype of female pseudohermaphroditism?

A
  • Retention of the urogenital sinus
  • Fusion of labia
  • Virilization via increased androgens: advanced skeletal “age”, clitoromegaly, and other ambiguities of genital anatomy
102
Q

What are the gonads often referred to as w/true hermaphrodites?

A

Ovotestis

103
Q

For true hermaphrodites, XX are generally raised as (male/female)?
Does spermatogenesis occur?
What genetic sx are common?

A
  • Female
  • No, because Y genes not present
  • Ambiguous genitalia; cryptocordism (undescended testes), and hypospadias are common (penis opening not at tip but underside)
104
Q

What are some possible genetic causes of true hermaphroditism?

A

Possible SRY translocation or loss of Rspo1 gene (testes repressor)
- No spermatogenesis because other Y genes not present

FHB Hormone/Repro (16 decks)

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