Abstract: To preprocess a tissue sample, a first permeable mesh membrane is tautly stretched out over the tissue sample and overlaid on top of a flat surface. This covering sandwiches and secures the tissue sample in between the first permeable mesh membrane and the flat surface. If it is desired to reinforce the mechanical strength of the first permeable mesh membrane, a second permeable mesh membrane can be tautly stretched out and overlaid on top of the sandwich. Alternatively, the second permeable mesh membrane can be attached onto a third component, such as a disposable solvent resistant frame, to create a framed mesh. Thereafter, the first permeable mesh membrane may be attached to the framed mesh to create a compound framed mesh. The tissue sample may then be sandwiched and secured in between the compound framed mesh and the flat surface. To retain and flatten the tissue sample, gentle pressure may be uniformly applied.