hi lacinda,
i've done just that....crystal mount the slides and then coverslip over with
permount and a coverslip.  i've found though that if you use a pipet to get
the surface nice and thin over the tissue and then dry them on a hotplate
you get pretty good optics for photography....not as good as a
coverslip....but close.
carrie kyle-byrne
eire@teleport.com