1. The document discusses the process of tissue processing for light and electron microscopy. This includes fixation, dehydration, clearing, infiltration, embedding, sectioning, staining, and mounting of tissue samples. 2. Key steps in electron microscopy are fixation with glutaraldehyde and osmium tetroxide, embedding in plastic resin, sectioning with an ultramicrotome, and staining with heavy metal stains for high resolution imaging of cell structures. 3. Immunohistochemistry uses antigen-antibody reactions to identify and localize specific molecules in tissue. Primary antibodies attach to antigens and secondary antibodies tagged with markers like HRP or fluorescent dyes are used for visualization.