This week, we’re just going to spend just a little bit of time talking about all the various types of chemical stains used in medicine. This will be helpful for those currently in pathology, but if you can understand this for histology, it will make life a lot easier.

So, these stains are kind of important for being able to read lab slides of various tissues and whatever they might throw at you. First, though, why do we use different types of stains? Essentially, what we’re doing when ordering a lab test, we want to specifiy what it is we’re looking for. Think of it like jumping on Google maps or something similar. If you highlight all the features on the map, so you can see absolutely everything, it is jumbled and overwhelming. Altogether, a map with too much detail is unhelpful. If, instead, you can turn on just what you are interested in, for instance beaches known for good snorkeling, you can survey the image and understand much easier. Similarly, picking the right stain is about highlighting what you’re most interested in.

H&E: routine stain for cellular detail
Prussian Blue: stains iron blue
Luxol Fast Blues: stains myelin blue
Per-iodic Acid-Schiff: stains high carbohydrate content molecules (like mucus) magenta
Masson trichrome: stains fibrous scar tissue turquoise
Reticulin: stains collagen type III molecules black
Congo Red: stains amyloid orange-red
Gram stain: stains bacteria for postive and negative. We have a whole article on this.
Acid Fast (Ziehl-Neelson): stains acid-fast bacteria, usually mycobacteria.