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    Akodon Fertile XY Female Rodents Defy Disorder Of Sex Development (DSD) Label
    By M Italiano | May 13th 2010 02:01 AM | Print | E-mail | Track Comments
    About M

    My undergraduate mentor was Elof Axel Carlson whom I consider a great friend. I graduated from a medical school in India with an MB BS (AM). This...

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    I am constantly amazed at how pathologizing variable phenomena is usually a human social agent. Consider the XY fertile Akodon females who go roaming around in South America. No other rodents seem to have told these fertile XY females that they have a  disorder of sex development (DSD). That will undoubtedly be left to some of the "powers that be" of the human species. Shall I say rats? Or shall I say of mice and men?

    These Akodon rodents are not classic mice or rats even though they are rodents. The XY fertile females of several Akodon species have a mechanism whereby the XY females are even more fertile than their XX female counterparts. This compensates for the wastage of the YY zygotes. Not only do these XY fertile female Akodon not have an SRY alteration when compared with their  XY male "brothers and friends", but these XY fertile female Akodon seem to have a mechanism which commonly allows for female fertility in the presence of an XY karyotype.

    Yet the methlylation status of the SRY sequence is not known in either the somatic tissue or in the germ line. A silencing of SRY sequences by methylation may prevent against harmful SRY products.  Furthermore, there is some evidence that the Y the X may undergo self-synapsis. Thus, there may be reverse silencing or inactivation (with respect to the karyotype) that occurs in X or Y genes during oogenesis that is influenced by the phenoype with which the chromosomes are found in (oocyte), that does not parallell that which typically occurs during spermatogenesis.

    In cases of a lack of typical (or even maybe even in the presence of self) synapsis, there may be an inactivation of meiotic genes that would typically and otherwise be active and important for germ cell viability. Data from  MSCI and MSUC tell us this. Furthermore, these XY fertile Akodon females have a higher rate of preimplantation development and have a longer reproductive lifespan than the XX fertile female Akodon. The fertile XY female Akodon start to reproduce early, they have more frequent litters, and stop reproduction later than their XX female counterparts.

        They are a puzzle and they are clearly a variation. They can tell us alot about the diversity of
    development. Pehraps this occurs in humans and goes largely unreported. In either case, they provide yet another model of variation (or VSD) or biosex variation as opposed to DSD.