Embedding of bone samples in methylmethacrylate: an improved method suitable for bone histomorphometry, histochemistry, and immunohistochemistry.

Methylmethacrylate (MMA) embedding of undecalcified bone biopsies is a technique widely used for bone histomorphometry. However, conventional MMA embedding causes almost complete loss of enzyme activity and protein antigenicity in the tissues. Recently, an MMA embedding technique has been reported that preserves enzyme activity and antigenic determinants in bone tissue. We describe here a modification of this embedding method. For our modified MMA embedding process, commercially available methacrylates can be used without purification, and the histologic quality of bone sections is comparable to that of conventionally MMA-embedded bone specimens. The technique reported here can be employed for embedding of larger bone samples and is suitable for histochemical and immunohistological applications as well as for routine bone histomorphometry. By addition of methylbenzoate during infiltration and polymerization of the plastic, the antigenicity of the tissue was improved. As applications of this novel technique, demonstration of alkaline phosphatase and tartrate-resistant acid phosphatase as well as positive labeling of Kupffer cells and osteoclasts with the monoclonal antibody ED1 in sections of liver, tibiae, and vertebrae of 3-month-old rats was demonstrated. The method described here might be useful for the inclusion of histochemical and immunohistological methods into bone histomorphometry.