Because biological samples contain various tissue elements, their properties (including soft and hard level, loose, density, size) will be different. In natural state, it is almost impossible to cut them into slice from dozen micros or even few micros. Embedding is to immerse some specific supporting materials into the tissue block, utilize their physical property (eg.changing from liquid state to solid state) to make the whole tissue with uniform solid structure and enough hardness so that very thin sections can be cut by slicer. Use paraffin as embedding medium and put the immersed tissue block into paraffin to make into paraffin block, which is the most commonly used embedding method. Paraffin section will keep good tissue structure that has bigger practical value in pathology and retrospective study, which allows continuous slicing with clear tissue structure and accurate antigen location.>>《“Preparation Method for Paraffin Section”》

Frozen section uses water as supporting materials to embed tissue specimen and perform slicing. Directly freeze the immobilized (or not) fresh tissue hardly for slicing rather than go through a series of dehydration, lucency, waxing and embedding. Tissues will not go through organic solvent treatment without the high temperature influence of waxing and embedding. Therefore, it will easily keep various enzymes, antigen activities and structures of fat, lipoid. In addition, the process for frozen section is very easy and generally only needs more minutes. However, it is preferred to have small tissue block for frozen section that shall be thicker than paraffin section, which is normally 8-80μm. Due to the worse resolution, it cannot be used for retrospective study and the section specimen shall not be kept for a long time. >>《 “Preparation Method for Frozen Section”》