INFLUENCE OF FIXATION PROCEDURE, EMBEDDING MEDIUM AND SECTION THICKNESS ON MORPHOMETRIC DATA IN THYROID-GLAND

The effects of fixation procedures, embedding medium and section thickness on stereological measurements of normal [mouse and rat] thyroid were analyzed. Use of a single section for lobe analysis is sufficient if this section is located in the central part of the lobe. Fixation and embedding with glutaraldehyde-Epon leads to a larger shrinkage than Bouin-paraplast, but the difference between the 2 procedures is not significant. Os post-fixation reduces the shrinkage induced by glutaraldehyde and lowers the axial deformation produced by sectioning. Bouin''s fixative and paraplast embedding induce considerable shrinkage of the interstitial tissue. The shrinkage obtained with glutaraldehyde-Epon is less. It is not known whether this difference is due to fixative, or to embedding procedure or to both. Only in glutaraldehyde and Os-fixed material, embedded in Epon, can follicles and colloids be assumed to be spherical in shape without significant errors.