NGW2 eyepiece reticles, Weibel 2

The Mertz Graticule (36 Points) - NGM1

Used when making a surface to volume ratio of a structure per mass unit. This graticule consists of a number of short lines with interruptions as long as the lines. Basically, the number of intersections falling over the short lines is counted and the number of endpoints falling on the end of the structure is determined.

In this simplest form, sterology is the science where information about a three dimensional object is obtained from only a two-dimensional section of that structure.

Measurements are usually made with these graticules in the following manner:

1. An adequate representation of sections of a specimen is obtained.
2. The graticule is superimposed upon the specimen (or micrograph/projected image of the section).
3. Finally, the interaction between the superimposed graticule and the test sections are recorded.

An overall introduction is given by: L.B. Brianrty. "Stereology: Methods for Quantitative Light and Electron Microscopy."

Reference

• E.R. Weibel, Journal of Microscopy Vol. 95. pp 373-378. Current Capabilities and Limitations of Available Sterrological Technique, point counting method.