H&E Staining: What It Is and How It Works

If you have ever seen a picture of tissue under a microscope — pink swirls with dark purple dots — you were almost certainly looking at an H&E stain. H&E is short for hematoxylin and eosin, the two dyes used in the most common staining method in histology, the study of tissues. It has been the everyday workhorse of laboratories for well over a century, because it is reliable, affordable, and shows an enormous amount of detail. This guide explains, in plain language, what the two dyes do, how a sample travels from the laboratory bench to the microscope slide, and how to get good results.

Two dyes, two colors

Fresh tissue is almost transparent. Under a microscope, everything would look like clear glass on clear glass. Staining adds color so the different parts of the tissue stand apart.

Hematoxylin colors the parts of the cell that are acidic, above all the nucleus — the control center that holds the cell's DNA. Hematoxylin stains nuclei a deep blue-purple, contrasting with the pink eosin background.

Eosin colors the parts that are basic: the cytoplasm (the body of the cell around the nucleus) and the connective tissue that holds everything together. These come out in shades of pink.

Put together, a trained eye can read the slide almost like a map: where the cells are, how they are arranged, and whether the tissue's normal pattern looks orderly or disturbed.

The journey of a sample, step by step

A finished slide looks simple, but a sample goes through several stages before it can be stained:

1. Fixing. As soon as tissue is removed, it starts to break down. It is placed in a fixative such as 10% neutral buffered formalin, which locks the proteins in place and preserves the tissue's structure.
2. Processing and embedding. Water is gradually removed from the tissue and replaced with melted paraffin wax. When the wax cools, the tissue sits inside a small solid block — firm enough to slice.
3. Sectioning (thin slicing). Using an instrument called a microtome, the block is cut into slices only a few micrometers thick — so thin that light can pass through them. Each slice is floated onto a glass slide.
4. Staining. The wax is removed, and the slide passes through hematoxylin, then eosin, with rinses and a few helper solutions in between. (TissuePro's step-by-step H&E staining protocol is on our Download SOP page.)
5. Coverslipping. A thin glass cover is mounted over the tissue with a drop of mounting medium. This protects the section and makes it clear for viewing. The slide is now ready for the microscope, and it can be stored for years.

Which kit size do you need?

TissuePro offers the same two-stain pairing in two sizes:

• The 500 mL Hematoxylin Eosin (H&E) Staining Kit — full-size bottles of Harris Hematoxylin and Eosin Y solution, suited to laboratories that stain regularly and in volume.
• The Hematoxylin Eosin Staining KIT (20 mL) — small dropping bottles of the same two stains, handy for teaching, small batches, checks, and counterstaining (adding a background stain to slides prepared for immunohistochemistry, a method that uses antibodies to mark specific proteins).

You can browse both, along with the individual stains, in the Staining Solutions collection.

A few honest tips for better results

• Good staining starts with good fixation. If the tissue was fixed poorly or too late, no stain can repair the damage. Fix promptly, in plenty of fixative.
• Keep your reagents fresh and clean. Old or contaminated solutions are a common cause of weak, uneven staining. Filter or replace them when results start to fade.
• Be consistent with timing. Leaving sections in a dye longer or shorter changes the result. Many laboratories time each step — for example, a few minutes in each solution — and write the times into their own protocol so every batch comes out the same.
• Change one thing at a time. If results look wrong, adjust a single step and test again. Changing everything at once makes the real cause impossible to find.

A short word about safety

Hematoxylin and eosin solutions are laboratory chemicals. Read the safety data sheet (SDS) before you start — ours are on our Safety Data Sheets page — work in a ventilated area, and wear gloves and eye protection.

TissuePro products are for laboratory and research use only. Not for drug, household, or other uses.

Ordering in volume for your laboratory? Contact customerservice@tissueprotech.com for bulk pricing.