Natural Exceptions to Normal Gonad Development in Mammals

@article{Jimnez2012NaturalET,
  title={Natural Exceptions to Normal Gonad Development in Mammals},
  author={Rafael Jim{\'e}nez and Francisco J. Barrionuevo and Miguel Burgos},
  journal={Sexual Development},
  year={2012},
  volume={7},
  pages={147 - 162}
}
Gonads are the only organs with 2 possible developmental pathways, testis or ovary. A consequence of this unique feature is that mutations in genes controlling gonad development give rise not only to gonadal malformation or dysfunction but also to frequent cases of sex reversal, including XY females, XX males and intersexes. Most of our current knowledge on mammalian sex determination, the genetic process by which the gonadal primordia are committed to differentiate as either testes or ovaries… 
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Known cases of XY and XX sex reversals described in mammals are reviewed, focusing mostly on domestic animals where sex reversal pathologies occur and on wild species in which deviations from the usual XX/XY system have been documented.
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It is shown that M. oregoni has lost an independently segregating Y chromosome and that the male-specific sex chromosome is a second X chromosome that is largely homologous to the maternally transmitted X.
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The XX/XY sex chromosome dosage and/or overexpression of the DAX1 gene on the X chromosome in the presence of a wild-type SRY gene may have caused this predominantly female phenotype.
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