ABSTRACT
Exercise 5.1 94 Exercise 5.2 96 Exercise 5.3 98 Exercise 5.4 99
5.1 Correcting for the effects of tissue shrinkage 80
This chapter describes how to estimate the number of discrete objects, for example, particles or cells, that are within a well-defined reference space. It can be achieved by estimating the number of particles per unit volume (numerical density) and then multiplying by the volume of the reference space. Alternatively total number can be estimated by use of the ‘fractionator’ technique. In many ways this is the core chapter of this book because it is in the area of number estimation that stereology has had its largest impact to date. An editorial in the Journal of Comparative Neurology stated in 1996 (Coggeshall and Lekan, 1996; Saper, 1996):
Beginning with this issue, we would like to establish a policy that we will attempt to apply to all papers that are henceforth submitted to the journal… that stereologically based unbiased estimates are always preferable for
establishing absolute counts or densities of structures in tissue sections. We expect that any papers that use simple profile counts, or assumption-based correction factors, will provide adequate justification for these methods, which will stand up to critical review. Referees are urged to consider this justification, and to insist on unbiased counts when it is not adequate.
