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MVST1B HR > Sexual differentiation > Flashcards

Sexual differentiation Flashcards

1
Q

D: Sex

A

the process by which a genetically novel individual is formed as the result of mixing of genes from two or more individuals

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2
Q

is the female homogatetic?

A

yes in humans.

not always teh case for other organsisms

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3
Q

how did the y chromosome evolve?

A

male sx determining gene on the proto Y chromosome

male advantageous genes accumulate

inversions prevent recombination. - evolve separately

non coding repetitive sequences deleted.

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4
Q

what is your gonadal sex?

A

determine by the genetic sex

whether you have a testis or an aovary

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5
Q

what is your somatic sex?

A

whether you have a penis scrotum & prosatate

vs clit vagina uterus and oviduct

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6
Q

what is your neuroendocrine sex?

A

HPG axis

whether its constant (male) or cyclical (female)

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7
Q

describe turnedrs syndrome

A

where you only ahve a single X chromosome

(depends if it comes from the mother or father)

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8
Q

what is kleinfelters syndrome?

A

XXY

bascially a male

small poorly functioning testicles.

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9
Q

how can you have an XX male?

A

when part of the sex determining region of the Y is translocated onto the X chromosome

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10
Q

can you have an XY female?

A

yes - sex determining part fo the Y is deleted

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11
Q

what is SRY

A

encodes DNA/RNA binding protein 200 AA long

has the HMG box - which binds DNA

its a transcription factor

Binds to other genes eg SOX9 – initiates cascades of gene expression.

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12
Q

Genital ridges form during _th and _th weeks on medial side of the mesonephric ridges

A

Genital ridges form during 5th and 6th weeks on medial side of the mesonephric ridges

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13
Q

what colonises the genital ridges?

A

Colonised by primordial germ cells migrating from the extraembryonic mesoderm close to the yolk sac.

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14
Q

wehat happens to the genital redges in males?

A

they form the sex cords - becoming the spermatogenic tubules

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15
Q

what happens to the sex cords in females?

A

sex cords break down – form clusters of cells aroud each PGC – become follicles

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16
Q

describe how the testis forms in males

A
  • SRY switched on in cells of the sex cords (sertoli cells)
  • sertoi cells proliferate to form seminiferous tubules
  • SRY also switched on in stromal cells (Leydig cells)
  • Seminiferous tubules connect with degenerating mesonephric tubules of the rete testis.
  • Androgens from Leydig cells maintain the mesonephric duct, and MIS from Sertoli cells stimulates degeneration of the paramesonephric duct.
17
Q

Androgens from Leydig cells maintain the ______ ____, and MIS from Sertoli cells stimulates degeneration of the _______ _____

A

Androgens from Leydig cells maintain the mesonephric duct, and MIS from Sertoli cells stimulates degeneration of the paramesonephric duct.

18
Q

leydig cells secrete?

A

androgens

19
Q

sertoli cells secrete?

A

MIS

20
Q

describe how the ovaries are formed in females:

A
  • no SRY
  • Sex cords degenerate
  • Coelomic epithelium proliferates to form cortical cords.
  • Cells from cortical cords surround oogonia to form primordial follicles.
  • Absence of androgens causes mesonephric duct to degenerate.
  • Absence of MIS permits maintenance of the paramesonephric duct.
21
Q

what does insulin like hormone 3 do?

A

stimulates the gubernaculuym to contract

= testis decent

22
Q

androgen cause the developemetn of what in males?

A

penis, scrotum

vasa,

accessort sex glands

23
Q

Differentiation of the external genitalia is driven primarily by…

A

Differentiation of the external genitalia is driven primarily by dihydrotestosterone (DHT)

24
Q

describe how DHTis produced

A

DHT is produced from testosterone by the activity of the enzyme 5 alpha reductase that is present in the local tissues

25
Q

Absence of this enzyme (% alpha Reductase) leads to…..

A

Absence of this enzyme leads to female genitalia (Guevodoces)

26
Q

describe Güevedoce

A

Güevedoces (roughly translated as “penis at twelve”) is a term used in the Dominican Republic for children with a specific type of intersexuality.

Güevedoces are classified as girls when they are born but, around the age of 12, they start developing male genitalia. T

his is due to a deficiency in the production of 5α-reductase, an enzyme involved in the metabolism of testosterone to dihydrotestosterone.

puberty = lots of testosterone = male charactertisics develope

27
Q

wat drives external gential developement

A

5 alpha reductase – testosterone –> DHT – drives external genetalia development

28
Q

in what ways may the bain be masculinised?

A

Structural – e.g. size of certain areas

Chemical – e.g. level of transmitters

Physiological – e.g. metabolism, cyclicity

Psychological – e.g. gender, aggression

Cognitive – e.g. verbal fluency, spatial ability

29
Q

Primary hermaphroditism

describe1

A
  • Anomalies of gonad
  • Ovary one side, testis on other
  • 2 gonads – mix of gonadal tissue – non functional
    • Mutational event during gestation – early – don’t cross midline = truw hermaphrodite
      • Later in developemtn – moscaisism = mix
30
Q

describe secondary hermaphrodiatism

A

anomalies of the soma

Testicular feminisation (androgen insensitivity syndrome)

Congential adrenohyperplasia

Micropenis

Hypospadias

31
Q

describe

Androgen insensitivity syndrome
(testicular feminisation)

A

XY male

normal sexual appearance

normal internal testis and androgen production

MIS production = no paramesonephric duct

external genitalia = female

no uterus, fallopian tube or upper vagina

  • 400 mutations known in androgen receptor – altering its function in many parts of life cycle.
  • Leads to spectrum – depending how function AR is
32
Q

describe congenital adrenal hyperplasia

A
  • 21 hyroxylase dysfunction - an enzyme used to produce cortisol. leads to precursor build up = more testosterone.
  • XX people can end up with lots of testosterone
  • = masulinisaed external genitalia
33
Q

describe 5-alpha-reductase deficiency

A

Guevedoces

XY people. lacking potent DHT

lack of external male appearance at birth

puberty = lots of testosterone - start developing of external genitalia (albeit small)

34
Q

Psychosexual development: what do these terms mean

Gender identity –

Gender role –

Sexual orientation –

A

Psychosexual development:

Gender identity – self representation

Gender role – toy preferences, physical aggression – society dependant

Sexual orientation – erotic interes

35
Q

is gencer learned?

A
  • Evidence for yes – depending on how you trewaat your babies
  • Babies repsonses – toys and clothes, environment
  • 2-4 years – learn gender role
  • Learn how to play the gender role
  • By 5 – fixed about gender – male or female – leads to gender policing of each other.
  • If boy behaves like a girl – children police this
36
Q

what is sexuality?

A

Classed by object of erotic attraction

Sexual sterotypes; behaviours

37
Q

is sexuality fixed?

A

no

38
Q

Man ____ likely to identify as gay rather than bisexual

A

Man more likely to identify as gay rather than bisexual

39
Q

fat

A

mamba

MVST1B HR (13 decks)

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