Positive feedback on hypothalamic cells t estrogen

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positive feedback on hypothalamic cells T (Estrogen) masculinizes the brain and in the process renders M hypothalamic cells unable to switch to positive feedback
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Brain Activation to Pheromones AND—pheromone released by M EST—pheromone released by F PET scan (rCBF) Controlled for odor areas Found activation in the hypothalamus (MPA & anterior) Heterosexual M show a response to F pheromone and not to M pheromone Heterosexual F show a response to M pheromone and not to F pheromone Homosexual M show response the the M pheromone and not to the F pheromone Homosexual F were not tested
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Genetic Studies of Homosexuality One of the most frequently cited studies of homosexuality was that of Kallmann (1952) in J Nerv Ment Dis: He reported 100% concordance in identical twins for homosexuality, 12% in fraternal twins Subsequent studies have failed to repeat Kallman's findings. Kallman later himself postulated that this impressive concordance was an artifact due to the fact his sample was largely drawn from mentally ill patients. The largest twin study 56 pairs of identical twins, 54 pairs of fraternal twins, 142 non-twin brothers of twins and 57 pairs of adoptive brothers. They found that the concordance rate of homosexuality for: genetically unrelated adoptive brothers was 11% for non-twin biologic brothers about 9% the rate for fraternal twins was 22% and for identical twins it was 52% Rem: this reflects variability accounted by genetics; Note: would also reflect common environmental factors during development
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Chromosomal Determination of Sexual Orientation. Male twins that are concordant for homosexuality share a portion of the X chromosome. Genetic determinant of sexual orientation: Has been replicated in one of two additional populations by the same group of investigators. Point to ponder: If homosexuality is a gene, how could the gene survive? Surely it would have disappeared due to homosexuals fathering less children? Role of epi factors or epi genetic markers
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  • Spring '13
  • WOODS
  • estrogen

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Christopher Reinemann
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