A major problem confronting researchers attempting to carry out in situ hybridization reactions is the lack of instrumentation dedicated to in situ work. Problems arise when attempting to contain the reaction components on the section during the hybridization process. Attempts to solve this problem using coverslips and a variety of sealing components can lead to failure. This is usually due to failure of the sealing components, allowing the reaction mixture to leak out from under the coverslip, and the subsequent drying of the specimen.