Trisha - 
     
     Brain research carries larger sized coverslips.  
     www.brainresearchlab.com.
     
     Also, in the past when I did very large sections I cut my own 
     coverslip to fit the sample.  I bought the glass in sheets 5"x 7" and 
     cut with a diamond etching pen.  It worked great but hopefully you 
     will not have to spend the extra time it took. THAT company was Roboz 
     and they used to be located in Washington, D.C. Contact me directly if 
     you need more specific information.
     
     
     Vicki Kalscheur
     School of Veterinary Medicine
     2015 Linden Drive West
     University of WI - Madison, WI  53705-4098
     
     (608) 262-8534     Fax (608) 263-7930      
     
     kalschev@svm.vetmed.wisc.edu