The Automatic Proportionator Estimator Is Highly Efficient for Estimation of Total Number of Sparse Cell Populations.

Rogely W Boyce,Hans J G Gundersen

doi:10.3389/fnana.2018.00019

Rogely W Boyce, Hans J G Gundersen

Open Access

https://doi.org/10.3389/fnana.2018.00019

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Abstract

Estimation of total number of a population of cells that are sparsely distributed in an organ or anatomically-defined region of interest represents a challenge for conventional stereological methods. In these situations, classic fractionator approaches that rely on systematic uniform random sampling are highly inefficient and, in many cases, impractical due to the intense sampling of the organ and tissue sections that is required to obtain sufficient counts for an acceptable level of precision. The proportionator, an estimator based on non-uniform sampling theory, marries automated image analysis with stereological principles and is the only estimator that provides a highly efficient and precise method to address these challenging quantification problems. In this paper, the practical considerations of the proportionator estimator and its implementation with Proportionator™ software and digital slide imaging are reviewed. The power of the proportionator as a stereological tool is illustrated in its application to the estimation of the total number of a very rare (~50/vertebrae) and sparsely distributed population of osteoprogenitor cells in mouse vertebral body. The proportionator offers a solution to neuroscientists interested in quantifying total cell number of sparse cell populations in the central and peripheral nervous system where systematic uniform random sampling-based stereological estimators are impractical.

Highlights

The optical and physical fractionators have been the stereological method-of-choice for obtaining unbiased estimates of total cell number for nearly three decades (Gundersen, 1986; West et al, 1991)
The automatic proportionator offers many advantages compared with other sampling and estimation strategies, notably the relative immunity of the proportionator to sparseness and inhomogeneity
The degree of sparseness of these osteoprogenitors in the mouse vertebra has not been properly defined, but one may index this by a ratio of the total number of zero count tiles/tiles with a count

Summary

Introduction

The optical and physical fractionators have been the stereological method-of-choice for obtaining unbiased estimates of total cell number for nearly three decades (Gundersen, 1986; West et al, 1991). The statistical robustness of the fractionator principle relies on the precision and efficiency of systematic uniform sampling to obtain an estimate of cell number from a final fraction of the organ/region of interest for cell counting (Gundersen, 1986). When the total population of the cell of interest is small and/or sparsely distributed, fractionator sampling becomes laborious and prohibitively inefficient. To obtain sufficient counts for an acceptable level of estimate precision (∼100–200 counts), intense sampling of the organ and tissue sections is required because many sampled fields will not contain the cell of interest.

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