Methyl Methacrylate Embedding of Large Nervous Tissue Blocks for Neurohistologic, Immunocytochemical, and Ultrastructural Studies

Celloidin embedding, despite its drawbacks, has been the method generally used for preparing histologic sections of whole brains, hemispheres, or other large neuroanatomical structures. Methyl methacrylate is a practical alternative that allows the embedding of specimens up to the size of a whole brain, preparation of histologic sections from 1-mu-m to 30-mu-m in thickness, and staining with conventional or special histologic stains (after appropriate modifications). Immunocytochemistry can also be performed on sections with standard peroxidase-antiperoxidase protocols. In addition, by using trimmed blocks of the same specimen, it is possible to prepare electron microscopy thin sections for ultrastructural examination. The technique of embedding tissue sections in methyl methacrylate maintains accurate neuroanatomical and neuropathological relationships without cytoarchitectural distortion, thereby facilitating accurate qualitative and quantitative studies. Additionally, sections of the same specimen can be assessed using multiple histologic and histochemical stains and by electron microscopy.