The Optical Fractionator probe lets you sample a 3D region of interest and estimate the total number of particles. It is an important development in probes involving the estimation of population size.
Watch these webinars: Unbiased Stereology to determine the number of cells in a region of interest, Implementing the Optical Fractionator Workflow
If you select Load subject data from existing file, typically directs you to the Count Objects step. Because the workflow is streamlined, only the relevant steps are displayed and they are re-numbered accordingly (e.g., Step 10 in the complete workflow might be referred to as Step 4 in the streamlined workflow).
Optical Fractionator (West, et al., 1991) combines the Optical Disector and the Fractionator for counting. It is unaffected by tissue shrinkage and does not require rigorous definitions of structural boundaries.
Optical Fractionator involves counting objects with optical disectors in a uniform systematic sample that constitutes a known fraction of the volume of the region being analyzed. In practice, this is accomplished by systematically sampling a known fraction of the section thickness, of a known fraction of sectional area, of a known fraction of the sections that contain the region of interest.
Use Optical Fractionator to perform systematic sampling of populations distributed within a series of serial sections to estimate the population number in a volume. Properly designed systematic sampling yields unbiased estimates of population number.
The theory underlying this sampling methodology also makes it possible to estimate the precision of the population size estimate for a single subject; this estimate of precision is called the Coefficient of Error (CE).
This CE should not be confused with the CE of estimates of the populations of the set of subjects that constitutes an entire experiment; the precision of population size estimates that are derived from a set of subjects is discussed later.