Now that we know what to expect from epithelial tissue, we are now ready to look at it microscopically.

Remember that tissue is normally clear and so we stain it to be able to distinguish the various parts of the tissue.

Hematoxylin and Eosin (H&E) Stain

H&E is the most commonly used stain and is a sequence of two different dyes.

Hematoxylin is a blue basic dye and stains acidic elements in the tissue such as the nucleic acids (RNA and DNA). Nuclei of cells, therefore, appear as blue circles.

Eosin is a pink acidic dye and attaches to basic molecules which are mainly proteins. These are usually found in the cytosol of the cells and in the extracellular spaces. Collagen, an extra-cellular matrix protein, stains pink as do muscle cells.

Purple staining in an H&E slide means that there is a combination of both acidic and basic elements. The keratin layer in skin often stains purple due to keratin (pink) and keratohyalin granules (dark blue)

Video Demonstration of Looking at the Histology of Epithelial Tissue

How do we look at tissues like a histologist?  This video demonstrates a histological description with H&E staining of thick skin.

Now let’s hear a histopathologist use these skills when describing lung epithelial tissue.

^{Introduction to Histology Staining by Dr. Jonathn Bush, licensed under All Rights Reserved}

Section Review

• Hematoxylin & Eosin (H&E) is the most common stain to visualize tissues.
  • blue = DNA/RNA within nuclei (usually, one nuclei/cell)
  • pink = protein (e.g. protein in intracellular fluid-like cytosol)
  • white = nothing to stain (e.g. air) OR stain can’t bind (e.g. fat)
• Nuclei are often the biggest structure within the cell – either in an oval or round shape.