It's easy to make mistakes and introduce artifacts when making a slide, therefore each of the foregoing steps must be done with great care.

What is the major purpose of each of these steps in tissue preparation for light microscopy?

• Fixation- cross-links proteins and preserves tissue structure by inactivating enzymes
• Removing the water in dehydration- helps prepare tissue for infiltration with paraffin
• "Clearing" with xylene or other organic solvent- replaces alcohol, gives tissue a translucent appearance, and aids in tissue infiltration by paraffin
• Embedding with paraffin- hardens the tissue in a paraffin block, rendering it suitable for sectioning with a microtome
• Sectioning with a microtome- allows thin sections, typically 3-10 microns thick, to be cut and subsequently placed on a glass slide
• Staining- most cells and tissue components are colorless and lack contrast, so histological dyes are used to differentially stain cell and tissue components
   

The histological primary stain.