Confocal stereology: an efficient tool for measurement of microscopic structures.

Quantitative measurements of geometric forms or counting of objects in microscopic specimens is an essential tool in studies of microstructure. Confocal stereology represents a contemporary approach to the evaluation of microscopic structures by using a combination of stereological methods and confocal microscopy. 3-D images acquired by confocal microscopy can be used for the estimation of geometrical characteristics of microscopic structures by stereological methods, based on the evaluation of optical sections within a thick slice and using computer-generated virtual test probes. Such methods can be used for estimating volume, number, surface area and length using relevant spatial probes, which are generated by specific software. The interactions of the probes with the structure under study are interactively evaluated. An overview of the methods of confocal stereology developed during the past 30 years is presented. Their advantages and pitfalls in comparison with other methods for measurement of geometrical characteristics of microscopic structures are discussed.