Nicola Parry
Articles by Nicola Parry:
A Beginner’s Guide to Haematoxylin and Eosin Staining
Once a tissue specimen has been processed by a histology lab, and transferred onto a glass slide, it needs to be appropriately stained for microscopic evaluation. This is because unstained tissue lacks contrast: all of the fixed materials have a similar refractive index and a similar color. If you viewed an unstained tissue section under…
Go For Gram! Staining Bacteria for Light Microscopy
The Gram stain is another commonly used special stain in the histology lab. Why use a Gram stain? The Gram stain is a type of differential staining technique which represents an important initial step in the characterization and classification of bacteria using a light microscope. It is named after a Danish scientist, Hans Christian Gram,…
Verhoeff-van Gieson Stain: A Special Histology Stain for Elastic Fibers
What is Verhoeff-van Gieson’s stain? Ira Van Gieson first described the Verhoeff-van Gieson (VVG) staining protocol in 1889 as a method of evaluating collagen fibers in neural tissue. Frederick Herman Verhoeff, an American surgeon and pathologist, then modified the stain in 1908, as a method to differentiate collagen and other connective tissues, and highlight elastic…
Toluidine Blue – A Histology Stain for Mast Cells (and Other Things!)
What is Toluidine Blue? Toluidine blue (TB) is a polychromatic dye which can absorb different colours depending on how it binds chemically with various tissue components. It first emerged in 1856, courtesy of a British chemist called William Henry Perkin. Although he was working on the synthesis of quinine, Perkin instead produced a blue substance…
Special Stains for Histology: An Introduction and Basic Overview
Routine tissue staining Haematoxylin and eosin (or H&E- see our H&E 101 articles here and here) is the most commonly used stain in histology labs, representing the ‘bread and butter’ stain for most pathologists who diagnose disease, and for researchers who work with many tissue types. It highlights the detail in tissues and cells, using a…
Don’t See Red! Use Oil Red O- A Histological Stain For Fats And Lipids.
What Does Oil Red O Stain? Oil Red O (‘ORO’) is used to demonstrate the presence of fat or lipids in fresh, frozen tissue sections. Introduced by French in 1926, ORO is a fat-soluble diazo dye, and is classified as one of the Sudan dyes which have been in use since the late 1800s. Like…
Prussian Blue- A Histology Stain For Iron
What is Prussian Blue? Prussian blue (PB) was actually the first synthetic color to be discovered during the Industrial Revolution. It was developed accidentally in 1704 by a chemist who was trying to produce another color. It wasn’t used as a histochemical stain until 1867 when its original formula was described by German pathologist, Max…
Congo Red – A Special Stain For Alzheimer’s Disease
What is Congo red? Did you know that Congo red (CR) originally started out as a textile dye? It belongs to the azo class of dyes- synthetic compounds that are among the most popular dyes used in the clothing and fashion industry. CR is a benzidine derivative which can react with structural polysaccharides- including the…
Acid Fast: A Histology Tool To Detect Bacteria and TB
What Does Acid-Fast Stain? Acid-Fast (AF) is an important special staining technique used in the histology lab. This is adifferential stain used to identify acid-fast bacterial organisms, such as members of the genus Mycobacterium and Nocardia. The discovery of TB German scientist and physician, Robert Koch, was a Nobel Laureate in Medicine and a founder…
How To Find Fungi In Your Histology Samples- Go For GMS!
Gomori’s methenamine silver (GMS) is another commonly used special stain in the histology lab. What Does GMS Stain? (1) Fungi GMS is probably best known for staining fungal organisms. Fungi are generally relatively large and morphologically diverse, and can occur in tissues in various forms: hyphae, endosporulating spores, budding yeasts, or a combination of these…
Starry Starry Night? No, Warthin-Starry Stain!
Continuing in our series, the Warthin-Starry (WS) stain is another type of special stain often in the histology lab to detect certain types of organisms. Why Use Warthin-Starry? Some Gram-negative organisms do not stain well by the Gram stain technique. These include spirochaetes (such as Helicobacter, Leptospira, Borrelia, and Treponema species), as well as small…
Why Pick PAS for Histology?
Periodic acid-Schiff (PAS) is another commonly used special stain in the histology lab. What Does PAS Stain? (1) Polysaccharides: The technique is commonly used to identify polysaccharides- these macromolecules are composed of monosaccharide units joined by covalent bonds. The main polysaccharide identified via histology staining in human and animal tissue sections is glycogen. This is…
Microscopists: Have you Tried Trichrome?
Have You Tried Trichrome? The trichrome stain is one of the most commonly used special stains in every histology lab. The pedantic meaning of the word trichrome is “three-coloured”, referring to how the technique differentially stains tissue samples in three colors. However, the term is now actually used to describe any staining method using two…
An Introduction to Special Stains
It’s unclear exactly how the term ‘Special Stains’ first arose in the world of histology, but it refers to empirical and histochemical staining techniques that significantly contributed to the advancement of histology in the late 19th century. In a nutshell, these stains are ‘Special’ because they are not routine – simple as that. Therefore, Special…
How Histology Slides are Prepared
If you’re involved in biological research, chances are at some stage you’ve submitted tissue specimens to a histology lab. Somehow they magically produced beautiful slides for you – each containing thin sections of your specimens, ready for microscopic evaluation. Have you ever wondered how the histology technician does this? Read on for the five important…
The Poor Man’s Polariser…Got Shades?
I recently introduced you to the concept of polarising microscopy. Naturally, if evaluating refractile material is an everyday part of your research, it is definitely worth investing in a professional polariser modification for your microscope. But if you only use a polariser occasionally, this might not be the best use of your lab’s money. In…
What You Ought To Know About Polarising Light Microscopy
Polarising microscopy involves the use of polarised light to investigate the optical properties of various specimens. Although originally used predominantly in the field of geology, it has recently become more widely used in medical and biological research fields too. Polarising light microscopy is a contrast-enhancing technique to allow you to evaluate the composition and three-dimensional…
How Köhler Illumination Can Help You See The Light
Although the microscope is probably the most commonly used biological instrument, it is frequently used improperly. The rate-limiting step to getting high quality microscopic images is illumination of your specimen. When you examine a specimen under the microscope, the intensity and distribution of light must be clear and equal to enable you to evaluate all…
What Everybody Ought to Know About the Light Microscope
If you’re starting your PhD or post-doctoral work, chances are you’ll need to use a light microscope at some stage during your research. Some of you may be seasoned microscopists. For many of you though, this might be the first time you’ve ever plugged in a microscope, or at least the first time you’ve used…