Hi Donna, I find Roche Molecular Biochemicals' Nonradioactive In Situ Hybridzation Application Manual very, very useful if you're doing ISH. Agripina C. Suarez McDonald Research Laboratories iCAPTURE Centre, St Paul's Hospital 1081 Burrard St, Vancouver B.C., Canada V6Z 1Y6 Tel no. 604 682 2344 local 62703 Fax no. 604 806 8351