The evaluation of large test fields for morphometric studies in electron microscopy.

The surface area of test fields required for morphometric evaluation of sectioned particles increases with the square of the mean particle diameter, but is inversely proportional to the volume fraction of the particles. A method is presented for an economical evaluation of large test fields. Factors giving rise to variation in the sampling procedure are analyzed. The volume fraction of autophagic vacuoles, for instance, shows a rather broad variation between animals, probably because of the short half-life of these particles. Other applications of the method include bile capillaries under different experimental conditions, and human biopsy specimens, e.g. liver tissue containing very few profiles resembling small peroxisomes in a case of Zellweger syndrome.