Effect of automatic and manual slicing on thickness variation of paraffin-embedded sections

Objective To observe the effect of automatic and manual slicing and tissue types on the thickness variation of paraffin-embedded sections.Methods Liver,pancreas,stomach and lung samples were obtained from five healthy adult male rats.Each tissue was separately embedded in paraffin.Slices were cut automatically and manually at various thickness set points,3,5,7,10 μm,by an automatic microtome.After the re-embedding vertical slicing and HE staining,the thickness of these slices was measured by a TIGER image analysis system.Results Only the automatic or manual slicing procedure exerted effect on the slice thickness.The slice thickness set points of microtome underestimated the actual thickness of paraffin-embedded slices.The thickness of auto-slice and manual slice were 29%～50% and 48 %～91%,respectively,thicker than the nominal thickness set on the microtome.Conclusion There is a 25% difference between the thicknesses of automatically cut slices and manually cut slices.The relative error rate of the two slicing methods is 61%.The precision of automatic cut thickness is higher,therefore,is better than manual sectioning.