I'm taking a look at the web page titled The Biology of Kundalini: The Science of Protocol of Spiritual Alchemy (from the AYP Links http://www.aypsite.org/Links.html)
The first line that really caught my attention was this one: "Although the traditions are focused on it, there is obviously no such thing as ejaculating up the spine."
That IS what it feels like sometimes, I can attest, but it is not what is actually happening biologically. I like the no-nonsense approach to the science side of Kundalini.
I think I will read more. Oh, now I remember, I surfed this page years ago. Nice to visit again.