Abstract: Slideholders which are useful for manually processing tissue samples on microscope slides are described. These slideholders hold multiple slides and are designed in conjunction with specialized trays for rapidly processing the mounted tissue samples such as for immunocytochemical staining. The slideholder plus tray assemblies incorporate several useful advantages including a requirement for minimal reaction fluid volumes, ease of handling several slides concurrently, prevention of evaporation of reaction fluids, protection of the tissue from extraneous environmental contamination, and the ability to perform in situ PCR. Various aspects of the design aid in removing trapped air from the reaction fluids and in adding fluids to the tissue sample. One embodiment comprises a coverslip with a soft top which aids in prevention of tissue degradation by preventing pressure buildup during PCR.