IF YOU ASSUME, YOU CAN MAKE AN ASS OUT OF U AND ME - A DECADE OF THE DISECTOR FOR STEREOLOGICAL COUNTING OF PARTICLES IN 3D SPACE

The year 1984 was a watershed in stereology. It saw the introduction o f highly efficient and unbiased design-based methods for counting the number of arbitrary objects in 3-dimensional (3D) space using 2D secti onal images. The only requirement is that the objects be unambiguously identifiable on parallel sections or successive focal planes. The mov e away from the 'assumption-based' and 'model-based' methods applied p reviously has been a major scientific advance. It has led to the resol ution of several problems in different biomedical areas. The basic pri nciple which makes possible 3D counting from sections is the disector. Here, we review the disector principle and consider its impact on the counting and sizing of biological particles. From now on, there can b e no excuse for applying the biased counting methods of yesteryear. Th eir continued use, despite the availability of unbiased alternatives, should be seen as paying homage to History rather than advancing Scien ce.