We are having an ongoing debate about the fixation times for paraffin sections that will be used for insituhybridization.  We have one researcher that is fixing whole cross sections of horse testis for only 24 hours in 4% paraformaldehyde.  12 of these hours are in the refrigerator. The tissues can be as big as a cassette will hold.  I was told that fixation for ISH is usually minimal and was wondering if it requires less than optimal fixation.  They are worried about over fixation, but the centers of the testis are obviously not fixed well.  Comments?  thanks, Sarah

Sarah LaBonte, HT (ASCP)
Research Associate, Histology Lab
Texas A&M University
College of Veterinary Medicine
Dept. of Vet Anatomy & Public Health
College Station, TX  77843-4458
phone: (979) 845-3177
fax:  (979) 458-3499