1.1 Macro versus micro
The conventional view of histopathology involves someone looking down a microscope. Indeed most histological work does involve preparation of tissues for microscopy, observation of sections and reporting of the findings. However a pathologist can often tell a great deal about a tissue without using a microscope. For example the brain of a person affected by multiple sclerosis has distinct lesions a few millimetres across called plaques in which myelin (the insulating element surrounding nerves) is damaged by inflammation. The plaques can readily be seen with the naked eye (Figure 1). Large specimens that can be examined macroscopically are usually only available post mortem or following surgical removal of tissue; biopsy specimens which consist of a needleful of cells or a flake of tissue can only be examined microscopically.