Sexual differentiation

Question 1

D: Sex

Answer 1

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

Question 2

is the female homogatetic?

Answer 2

yes in humans.

not always teh case for other organsisms

Question 3

how did the y chromosome evolve?

Answer 3

male sx determining gene on the proto Y chromosome

male advantageous genes accumulate

inversions prevent recombination. - evolve separately

non coding repetitive sequences deleted.

Question 4

what is your gonadal sex?

Answer 4

determine by the genetic sex

whether you have a testis or an aovary

Question 5

what is your somatic sex?

Answer 5

whether you have a penis scrotum & prosatate

vs clit vagina uterus and oviduct

Question 6

what is your neuroendocrine sex?

Answer 6

HPG axis

whether its constant (male) or cyclical (female)

Question 7

describe turnedrs syndrome

Answer 7

where you only ahve a single X chromosome

(depends if it comes from the mother or father)

Question 8

what is kleinfelters syndrome?

Answer 8

XXY

bascially a male

small poorly functioning testicles.

Question 9

how can you have an XX male?

Answer 9

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

Question 10

can you have an XY female?

Answer 10

yes - sex determining part fo the Y is deleted

Question 11

what is SRY

Answer 11

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.

Question 12

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

Answer 12

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

Question 13

what colonises the genital ridges?

Answer 13

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

Question 14

wehat happens to the genital redges in males?

Answer 14

they form the sex cords - becoming the spermatogenic tubules

Question 15

what happens to the sex cords in females?

Answer 15

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

Question 16

describe how the testis forms in males

Answer 16

• 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.

Question 17

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

Answer 17

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

Question 18

leydig cells secrete?

Answer 18

androgens

Question 19

sertoli cells secrete?

Answer 19

MIS

Question 20

describe how the ovaries are formed in females:

Answer 20

• 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.

Question 21

what does insulin like hormone 3 do?

Answer 21

stimulates the gubernaculuym to contract

= testis decent

Question 22

androgen cause the developemetn of what in males?

Answer 22

penis, scrotum

vasa,

accessort sex glands

Question 23

Differentiation of the external genitalia is driven primarily by…

Answer 23

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

Question 24

describe how DHTis produced

Answer 24

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

Question 25

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

Answer 25

Absence of this enzyme leads to female genitalia (Guevodoces)

Question 26

describe Güevedoce

Answer 26

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

Question 27

wat drives external gential developement

Answer 27

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

Question 28

in what ways may the bain be masculinised?

Answer 28

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

Question 29

Primary hermaphroditism describe1

Answer 29

* 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

Question 30

describe secondary hermaphrodiatism

Answer 30

anomalies of the soma ## Footnote **Testicular feminisation (**androgen insensitivity syndrome) **Congential adrenohyperplasia** **Micropenis** **Hypospadias**

Question 31

describe ## Footnote Androgen insensitivity syndrome (testicular feminisation)

Answer 31

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**

Question 32

describe congenital adrenal hyperplasia

Answer 32

* 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

Question 33

describe 5-alpha-reductase deficiency

Answer 33

Guevedoces XY people. lacking potent DHT lack of external male appearance at birth puberty = lots of testosterone - start developing of external genitalia (albeit small)

Question 34

Psychosexual development: what do these terms mean Gender identity – Gender role – Sexual orientation –

Answer 34

Psychosexual development: Gender identity – self representation Gender role – toy preferences, physical aggression – society dependant Sexual orientation – erotic interes

Question 35

is gencer learned?

Answer 35

* 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

Question 36

what is sexuality?

Answer 36

Classed by object of erotic attraction Sexual sterotypes; behaviours

Question 37

is sexuality fixed?

Answer 37

no

Question 38

Man ____ likely to identify as gay rather than bisexual

Answer 38

Man more likely to identify as gay rather than bisexual

Question 39

fat

Answer 39

mamba