Three-dimensional reconstruction from serial sections. V. Calibration of dimensional changes incurred during tissue...

Three-dimensional (3-D) reconstructions from serial tissue sections produce a table of x, y, z coordinates (i.e., a numerical description of the object) that will support 3-D computer graphics displays and morphometric analyses. While measures such as volume or surface area can be generated interactively, almost instantaneously, they are usually of unknown accuracy due to artifacts that may be introduced at two different stages: (1) tissue shrinkage during dehydration and polymerization of a plastic and compression or expansion during sectioning and mounting and (2) geometric and intensity distortions during image capture and data processing. This paper describes simple methods for (1) introducing fiducials (reference marks) that allow measurement of the net distortion incurred during tissue preparation and (2) estimating the amount of geometric distortion arising during image capture and data processing. Application of these methods showed that the net areal change introduced in dog and sheep hearts during tissue processing amounted to +/- 5%. Apparently, the substantial shrinkage that occurs during tissue processing is largely compensated for by the expansion during tissue sectioning and mounting. The methods described may have application to other semisolid tissues.