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Flashcards in sex determination Deck (23)
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what are the three parts to sex determinations

gonad formation, gonad determination, sex differentiation


what does the nephrogenic ridge develop into

The nephrogenic ridge develops into the mesonephric ducts or Wolffian ducts and the precursors of the urinary system


where does the Mullerian ducts arise from

The paramesonephric ducts or Mullerian ducts develop from further invagination of the intermediate mesoderm


where do the primordial germ cells migrate to

gonandal ridge to devlop into gonads


what gene drives testicular development in gonad determination

SRY expression, no sry and ovaries will be favoured in devlopment


to achieve sex differentiation what aspects of body need to be affected by hormones

internal extra tissue for gonads, external gentalia, internal reproductive organs


what regions of the x and y chromosome are the same

PAR1 and PAR2 on both ends of the chromosome


where is sry gene located and why is this a risk for sry translocation

sry is close to par1 which can lineup with par 1 on x chromosome poor crossing over can mover sry gene to x chromosome


what genes are important for teste formation

sry , sox9, dax 1


where is dax 1 located and what does it do

DAX1 (orphan nuclear receptor) • Gene on X chromosome • Represses testes development • Dosage sensitive • duplications lead to DSD in XY individuals, male only has one x chromosome therefore one dax1 so teste not repressed enough andcan develop. (issue in kinefellter xxy)


what does sox9 do

SOX9 • Gene on chromosome 17 • Acts on downstream targets to promote development of the testes • Dosage sensitive


what evidence suggest that formation of the ovaries requires two x chromsomes and is not a passive process

For a long time formation of the ovary was thought to be a passive process • However, the observation that women with Turner syndrome (45, XO) do not develop functional ovaries suggested that some factor on the X chromosome was required


what is the gonad called before gonad determination has occured

bi potential gonad because you can get testes or ovary


what hormones are involved in sex differentiation of a male

amh and testosterone dht


what does amh do in developing male

causes Mullerian duct regression


what does testosterone do

Testosterone promotes the development of the Wolffian duct into the epididymis, vas deferens and seminal vesicles


what does dht do

aggressive form of testosterone and drives external gentalia development


what enzyme converts testosterone to dht

5 alpha reductase


What are symptoms of 5 alpha reductase deficiency

Internal structures male • Variable appearance of external genitalia at birth • During puberty increased androgen levels lead to virilisation of external genitalia


what is kinefellter and its symptoms

47XXY Normal at birth, higher incidence of undescended testes • Tall stature • Small ‘pea-sized’ testes • Lack of secondary sexual characteristics • Gynaecomastia • Infertility • Some behavioural and minor learning difficulties


what does absence of AMH result in in female developing reproductive system

• The Mullerian duct develops into the fallopian tubes, uterus and upper vagina • The Wolffian duct regresses


does the development of external genitalia in a female require

does not require functional ovaries a bit of a trick question, vagina clit and labia will form by default


how can you treat sry translocation