Physical randomization of tissue architecture: an alternative to systemic sampling

A method is described for the rapid and accurate quantitation of tissue morphology using rat thyroid as a model. Perfused-fixed rat thyroid was diced into approximately thirty small pieces which were then randomly embedded in epon. Sections were taken at 500 micrometer intervals and stained with toluidine blue. Epithelial, follicular lumen and stromal components were quantified by a point counting technique. An analysis of variance was then performed on the data to determine whether there was any significant variation in the distribution of components between sections cut at different levels. No significant variation in any component was seen between sections for normal diced thyroid. This was also the case for diced thyroids of animals chronically treated with goitrogen to create a different physiological state. The method is therefore reliable even when marked changes in component distribution are induced. The physical randomization of tissue architecture by dicing, prior to embedding, greatly reduces the number of sections needed for the accurate morphometry of non-randomly distributed tissues.