Dr. Weeks’ Comment:   There is, after all, a difference between female sex hormones and male sex hormones.  Let us think on these wonders!

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Placental Precursor Stem Cells Require Testosterone-free Environment To Survive

ScienceDaily (Oct. 31, 2009) ”” Trophoblast stem cells (TSCs), cells found in the layer of peripheral embryonic stem cells from which the placenta is formed, are thought to exhibit “immune privilege” that aids cell survivability and is potentially beneficial for cell and gene therapies. Further, the survivability of TSCs has been thought to require the presence of ovarian hormones. However, none of these assumptions has ever been verified.

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When the research team injected the livers of both male and female mice with TSCs, the cells survived in female animal livers but did not survive in male animal livers.

“This was not unexpected, given the natural uterine environment for TSCs,” said Dr. Binas. “However, castration of the male mice abolished the sex hormone difference and the livers of the castrated male mice provided a perfect environment for the TSCs.”

The researchers concluded that the presence of male hormones was toxic for the injected TSCs. The injected TSCs survived for three months with little if any proliferation, regardless of their immunological compatibility, but were dependent on a non-male hormonal environment in castrated male mice.

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SOURCE http://www.sciencedaily.com/releases/2009/10/091029102430.htm