At 05:04 PM 4/12/99 -0400, you wrote:
>	I recently tried the fluorescent Filipin stain for cholesterol, as
>found in Bancroft and Stevens.  Problem is, I'm having a hard time finding
>any information about how the stain works.

  The filipin molecule attaches to cholesterol in cell membranes,
  and has been used as a label in electron microscopy. For a paper
  reporting its use, see:

  Pelletier, M & Vitale ML   1994.  Filipin vs enzymatic localization of 
  cholesterol in guinae pig, mink and mallard duck testicular cells. 
  J. Histochem. Cytochem.  42(12): 1539-1554.

  This is a paper in which filipin is used. The references might send
  you back to some of the basic science of the method. Sorry I
  can't provide anything better than this. (Perhaps Bancroft & Stevens
  has some refs - I don't own the latest edition so can't immediately
  check.)