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26 Cards in this Set
- Front
- Back
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Primary determination, presence of Y |
Absent: wnt4, Rspo1, bcatenin Present: sry, sox9, fgf9 |
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Rspo1 stimulates |
wnt pathway and bcatenin sythesis: -initiates ovary differentiation -prevents accumulation of sox9 no wnt = males |
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wnt4 |
first expressed in genital ridges of both sexes later not detectable in males without it ovaries do not form |
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XY with duplicated wnt and rspo1 genes |
bcatenin pathway overides sry/sox9 become female |
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Bcatenin |
activates ovarian transcription factors estrogen receptors form on ovaries |
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Bipotential gonad |
wnt is expressed, regulates Dax1 wnt is downregulated by xy maintained by xx |
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Dax1 |
located on x chromosome initially expressed in both sexes dax1 and sry overlap, in females this eventually becomes only dax1 antagonizes sry sox9 sf1 |
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Sry |
sex determining region of y chromosome short arm activates sox9, sf1 found in gonad before testi differentiation |
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xx with sry |
develops gonads |
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sox9 |
autosomal found in most vertebrates xx with extra sox9 become males one copy missing in xy -most are female or herm |
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sox9 roles |
activates its own transcription blocks bcatenin activates genes necessary for testis formation activates AMF activates some FGF |
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FGF9 |
sry needed for migration of mesonephric cells and sterioli induction FGF9 is also needed most likely regulated by sry or sox9 |
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SF1 |
steroidogenic factor 1 - forms bipotential gonad later downregulated in females regulates sf1 and amh with sry upregulates sox9 |
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Secondary sex determination |
1. phase one in fetus 2. puberty |
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Default sex is |
female, even without ovaries male require two hormones AMH and testosterone |
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Location of wnt |
in genital ridge activates female pathway in genital tubercule activates male |
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Testosterone and DHT |
testosterone - before birth - internal genitilia DHT - external genitilia Conversion dependent on 5ARD used in puberty for 2nd wave |
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5alpha reductase 2 deficiency |
inherited can convert testosterone to DHT |
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androgen insensitivity syndrome |
complete or partial, genetic XY, testes, synthesize testosterone, female brain young - beautiful female, becomes a male with defects second pathway -no testosterone receptor functional androgen receptors needed for full masculinization |
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Estrogen |
needed for development of mullarian and wolffian ducts sperm cannot be made without it - wrong concentration concentration high in rete testes F: derived in ovary, sufficient |
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Hemaphrodites |
ovarian and testicular tissues present 1. ovary at one side, testes at other 2. ovotestes - both tissues in one gonad Causes: late sry activation translocation of sry to x chromosomes |
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pseudohermaphrodites |
only one type of gonad secondary sex characteristics are opposite |
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Regulation of brain sex |
difference may be apparent before gonads are formed sry expression in brain over 50 genes expressed before gonad differentiation high aromatase in sheep oSDN, small oSDN in gay sheep |
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Male brain development |
testosterone to brain and converted to estradiol by aromatase estrogen binds to receptors to mascularize neural circuits and defeminize |
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Female brain development |
alpha feto protein binds to estradiol prevents it from entering the brain |
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sex determination in drosophila |
drosophila - xy and 3 pairs of autosomes start increasing in size and become polyploid balance of female determinants on x and male determinants on autosomes SEX LETHAL GENE y chromosome is only important for sperm formation xo males - sterile |
