For enzyme histochemical studies, tissue should be treated with 30% sucrose and 1% gum acacia and can be stored at 4°C for several weeks for which purpose?

• A. Enzyme histochemical studies
• B. Routine H&E staining
• C. Immunohistochemistry localization
• D. Electron microscopy

Answer: (A)

Enzyme histochemistry relies on preserving enzyme activity in the tissue, so the preparation is geared toward maintaining that activity during storage. Infiltrating tissue with a solution of 30% sucrose acts as a cryoprotectant, replacing water and reducing ice crystal damage that can disrupt enzyme active sites during freezing and storage. The 1% gum acacia adds viscosity and helps keep the tissue intact and limits diffusion of substrates or reaction products, helping to preserve the precise localization of enzymatic activity. Storing at 4°C slows degradation without inactivating the enzymes needed for histochemical reactions, allowing the tissue to be kept for weeks until processing.

This approach isn’t used for routine H&E staining, which requires fixation that preserves morphology but would destroy enzyme activity. It’s also not the standard for immunohistochemistry, which emphasizes antigen preservation, nor for electron microscopy, which requires strong fixation and resin embedding. The combination described is specifically to maintain enzymatic activity for enzyme histochemical studies.