![Human brain tissue sample with H&E stain of nuclei of the cells.](http://static.sciencelearn.org.nz/images/images/000/000/535/full/Biological-stains20151114-14989-1atfmh0.jpg?1674164452)
Scientists use stains to colour their samples of biological tissue before viewing them through light microscopes. Stains highlight particular components of the sample and make it easier to interpret. Here, a human brain tissue sample uses an H&E stain to emphasis the nuclei of the cells (purple).