The first group includes measurements of depths ? i.e., depth of decarburization, depth of surface hardening, or thickness of coatings or platings. Examples of the applications of stereological measurements have been reviewed by Underwood (2).īasically, two types of measurements of microstructures are made. At this time, true quantitative procedures are replacing chart methods for such purposes and they are gaining usage in quality control and research studies. Fortunately, there has been tremendous progress in the development of powerful, user-friendly image analyzers over the past two decades.Ĭhart methods for rating microstructures have been used for many years to evaluate microstructures, chiefly for conformance to specifications. What degree of counting accuracy can be expected when the subject is less familiar, such as microstructural features? Image analyzers, on the other hand, are quite good at counting but not as competent at recognizing features of interest. In this case the subject was one very familiar to the test subjects, yet only 3.8% obtained the correct count.
This experiment revealed a basic problem with manual ratings. Results were not Gaussian, however, as only 4.3% had higher values while 92% had lower values, some much lower. The correct answer was obtained by only 3.8% of the people. About 400 people were asked to count the number of times the letter “e” appeared in a paragraph without striking out the letters as they counted.
Many years ago, George Moore (1) and members of ASTM Committee E-4 on Metallography conducted a simple counting experiment. Further, while humans are quite good with pattern recognition, as in the identification of complex structures, they are less satisfactory for repetitive counting. This can be achieved through standard transcardial perfusion typically used to harvest other organs.Although the fundamental relationships for stereology, the foundation of quantitative metallography, have been known for some time, implementation of these concepts has been restricted when performed manually due to the tremendous effort required. Briefly, tissue should be well perfused with paraformaldehyde, glutaraldehyde, or formalin. Protocol Part 1: Pre-processing of tissue should be done according to Burke et al. In addition to contrast and comparison of results from both the BioQuant and Stereologer systems, this study provides a detailed protocol for the Stereologer system. This study documents a biological application of computerized stereology to estimate the total neuronal population in the frontal cortex of the vervet monkey brain (Chlorocebus aethiops sabeus), with assistance from two commercially available stereology programs, BioQuant Life Sciences and Stereologer (Figure 1).
Among the advantages of these stereological approaches over previous methods is the avoidance of all known sources of systematic (non-random) error arising from faulty assumptions and non-verifiable models.
The key components of the approach are unbiased (systematic-random) sampling of anatomically defined structures (reference spaces), combined with quantification of cell numbers and size, fiber and capillary lengths, surface areas, regional volumes and spatial distributions of biological objects within the reference space 4.
Unbiased stereology, the method accepted as state-of-the-art for quantification of biological objects in tissue sections 2, generates reliable structural data for biological features in the mammalian brain 3. The non-human primate is an important translational species for understanding the normal function and disease processes of the human brain.