Lecture 23

testis formation downstream of sry expression then

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Unformatted text preview: ertebrates. ! !Testis formation, downstream of SRY. ! •  Expression then disappears !Binds AMH promoter. Autosomal, XX humans with extra copy of sox9male, even w/o SRY! •  Transcription factor FGF9 - knockout homozygotes mostly female, regulated by sry/sox! ! SF-1: steroidogenic factor -1, transcription factor, activated by sry,! !-involved in Leydig cell testosterone production and ! !activation of AMH in Sertoli cells! Ability of sox9 to generate testes in wt and transgenic mice! Female differentiation genes:! (MIS)! ! No sox 9! No AMH! Testicular tissue! Genital ridge Embryonic gonad (sertoli cells) !Dax-1 : located on X, expressed in gonadal rudiment, overexpression antagonizes sry, sox9, downregulates SF1! ! !Wnt4: autosomal gene, initially expressed in bipotential phase, then undetectable in XY gonads, maintained in XX for ovary formation! Ovarian tissue! 3 5/1/13 Possible mechanism for primary sex determination in mammals:! Neither AMH nor testosterone produced, female phenotype! Secondary Sex Determination: Mammalian sexual phenotype is controlled by gonadal hormones! XY: Formation of male phenotype! ! AMH(Sertoli):degenerates Mull.Duct! Testosterone (fetal Leydig): converts W.ducts into epididymis, seminal vesicles, vas deferens! 5 alpha dihydrotestosterone: male urethra, prostate, penis, scrotum! ! XX: Formation of female phenotype! Estrogen: female genital tract! Postulated cascades leading to male and female phenotypes in mammals:! 4 5/1/13 Brain Sex: Sex Determinants and Behaviors in Mice and Rats Read Sidelights and speculaHons page 526, but beware of figure 14.14! This figure doesn’t seem to agree with Bakker and Baum 2008 orignal data Trends in health (past 20 ­50 years) What we do to the earth, we do to ourselves -Carolyn Raffensperger, Science and Environmental Health Network  3 million  ­ the reducHon in number...
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This document was uploaded on 04/03/2014.

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