I have been thinking about this a lot. You can either agree or disagree with my theory, but at least hear me out. I read in the list a couple of nights ago that sperm cells were now being considered as a treatment for P.D. That got me to thinking about the fetal tissue implants and GDNF. If all of these treatments end up working on Parkinson's disease, then there has to be something to the fact that all three of these things represent young tissue, Wouldn't it figure? I mean, GDNF is derived from glial cells, and it has been shown that it is present in the brains of developing fetuses. Next, the fetal tissue implant is just a transfer of the youngest brain tissue in the world. Finally, the sperm cell is, beside the egg itself, the most immature form of human tissue. So, doesn't it follow that there is some neurotrophin at work, not only generating cell growth, but protecting the existing cells. In other words, the cause of Parkinson's may be the depletion of this factor? Jacob Drollinger