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• Introduction
  • Design-Based Stereology
  • Symbols Used in Stereology
• Sampling
  • Fractionator Principle
  • SRS Preferential Sections
  • VUR Sections
  • IUR Sections
  • Faver Sections
• Counting Frame
  • Counting Rules
  • Disector
  • Optical Disector
  • Edge Effect
  • Optical Disector vs. Unbiased Brick
• Optical Fractionator
• Cavalieri Estimator
• Nucleator
• Estimators/ Probes
  • Length & Surface
• Coefficient of Error
  • CE and Biological Variability
  • CE and Study Design
  • Some CE Theory
  • CE Controversy
• References
  • Further Reading
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The Nucleator

Nucleator Local Estimator

The nucleator is a good method of estimating cell volume. An important requirement for the nucleator is that it requires the use of IUR or VUR sections or slices. See the sections on IUR sections or VUR sections for more information about this degree of randomness.

Use the nucleator to estimate the volume of a particle. The goal is usually to determine the mean volume of a population. To do this, it is important that the particles, usually cells or nuclei, are properly selected. The optical fractionator selects cells based on their existence. Each cell has the same probability of being selected regardless of the shape, orientation, or size of the cell. If the cells are not chosen in an unbiased manner, then the mean of the estimated volumes cannot be unbiased.

Follow the protocol for the optical fractionator to select those cells that are to be used in the study. For each cell that is selected apply the nucleator.

The requirement of the nucleator is that each particle in the sample has a unique, arbitrary point that can be identified. For cells, the point is usually the nucleolus. Cells with no nucleolus or multiple nucleoli cannot be used.

The optical fractionator should be applied to the nucleolus of the cell. The reason for using the nucleolus instead of the nucleus is that the nucleolus is smaller and easier to use when applying the counting rules of the counting frame. In terms of the nucleator, it does not matter if you use the nucleus or the nucleolus to select cells as long whatever choice is made is used throughout the sampling.

The nucleator can be used with either IUR or VUR sections or slices. The idea is to place one or more rays starting at the arbitrary point and preceding outward in an IUR fashion. Software can select the directions for you, or if a manual mode is being used, select the ray direction manually. In either case, make sure that the appropriate method is used to select an IUR direction. For software packages, make sure that the mode is set IUR or VUR sections.

For efficiency use either 2 or 4 rays. Two rays are situated so that they are oriented in opposite directions. Four rays form 2 lines that cross. More or fewer rays are possible, but are not useful when considering efficiency.