@farmerman,
Edited on Oct. 24, 2011: Reasons why they were blood vessels.
1.No minerals possess the shape and size of the “blood vessel remains”, which branch, curve,contain bulging dots, and measure around two micrometers in diameter.
2.No bacteria or fungi or plant rootlets have so many minute branches (~2 micrometers across) in such small areas.
3.No animal cells or tissues have such minute (~2 microns across) branches bulging with round dots, except blood vessels and lymph vessels. Lymph vessels should be connected to lymph nodes, which are not seen in the image.
So, blood vessels were the only real possibility.
A list of my posts:
Edit [Moderator]: Link removed
P.S. to farmer: Chrysotile or white asbestos is the most commonly encountered form of asbestos, according to wikipedia.