First-order stereology in diabetes and endocrine research-number and volume estimation of objects

ABSTRACT

Stereology is a technique that enables acquisition of data on number, volume, length or surface area of identifiable objects in a three-dimensional structure by sampling in two dimensions. That is, it provides a technique for quantifying objects on a slice from the structure such as a histological specimen viewed under the microscope or a computerised tomography [CT] scan. It has the enormous virtue of having a rigorous mathematical foundation and rules for counting that also give a reliable measure as well as an indication of precision. First-order stereology denotes estimating volume, surface area, length or number of any biological object. Terms such as degeneration, toxicity, atrophy hypertrophy, dysgenesis, and proliferation all refer to alterations in one or more of these parameters. However, as it is the case with almost all pertinent studies, it is not possible to count the number of relevant units directly. Yet the information is essential if we want to know how experimental or environmental interventions affect an organ's development. For example, what effect does the absence of a particular growth factor or reduced nutrition have on the number or size of islets, and at what stage of development does this occur; or has behavioural experience or environmental insult affected the number of chromophobes in the pituitary gland? The mainly unbiased and reliable way to obtain such information is by means of stereology. This technique is an absolutely essential tool for any biologist who needs to know the number of units in any system, whether they be functional units like number of islets within the pancreas, or cell organelles like mitochondria. It also provides a means of obtaining size, length and surface area of any object under consideration. In this review the current practical applications of two first-order stereology parameters in relation to diabetes and endocrine research are highlighted