calico cats and chimaeric mice

Kevin T. Merrell ktm3 at
Tue Jun 14 13:59:38 EST 1994

On 14 Jun 1994 Joanne_Ownbey at CBRC.MGH.HARVARD.EDU wrote:

>                       Calico cats vs. Chimeric mice?
> I now understand how one can have a male calico cat.  What confuses me is
> how can one get a female chimeric mouse made from presumably an XX
> blastocyst and known XY ES cells that can pass on the ES cell "trait" to
> the next generation?  The problem that I'm having is that if XY ES cells
> are contributing in any way to the gonad shouldn't you get a male
> phenotype.  And if the ES cells are not contributing to the gonad then the
> "trait" shouldn't be passed on to the next generation.  Any help in
> explaining this would be greatly appreciated.

I have wondered about this. Presumably if the es cells are a very minor
contributor to the ovary the mouse might still be phenotypically female
but I wonder if XY cells would develop into viable eggs in the ovary. My
own (probably worthless) theory on this is that the cells are actually
X0. (some portion of them having lost the Y chromosome) These cells would
then contribute to the ovary just fine. I had also heard that unlike
Turner's patients XO mice are fertile.
Kevin Merrell

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