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

Remember that tissue is normally clear, so we use stains to help distinguish its various components.

Hematoxylin and Eosin (H&E) Stain

H&E is the most commonly used stain and involves a sequential applications 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 binds 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 indicates the presence of both acidic and basic components. The keratin layer in skin often stains purple due to the combination of pink-staining keratin and dark blue keratohyalin granules.

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 listen to a histopathologist describe lung epithelial tissue using these skills.

^{Introduction to Histology Staining by Dr. Jonathan 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 the cytosol or other intracellular fluid)
  • White = nothing to stain (e.g. air) OR stain can’t bind (e.g. fat)
• Nuclei are often the biggest structure within the cell, and may appear in either an oval or round shape.