standard staining techniques Flashcards
4 steps of preparation of tissues for microscopic examination
Fixation
Embedding (dehydration, clearing)
Sectioning
Staining
Picric acid
enhances preservation of morphology in some tissues
Parafin wax
most commonly used waxes for infiltration.
solid at room temp but melts at temps up to about 65 oC OR 70 oC
Microtomes
are machines used to cut very thin slices of specimens embedded in the wax. they use steel, glass or diamond depending on the specimen and thickness required.
Longitudinal section
tissue is cut along the longest direction of the organ
Transverse section
Tissue is cut perpendicular to the length of the organ (also known as a cross section)
special stains
use a variety of dyes and techniques to stain particular tissues, structures and pathogens to assist pathologists with tissue-based diagnosis
Acidic pH
<7
Acidophilic Stains
higher concentration of H+
Some tissue molecules will bind H+ and will carry a positive charge
Basic pH
> 7
lower concentration of H+
Some tissue molecules will give up a H+ and will lose a positive charge
Hematoxylin & Eosin
most common histological stain
Alcian Blue
stains mucins blue
Masson’s trichrome
nuclei and other basophilic structures= blue
collagen= green
cytoplasm, muscle, erythrocytes, keratin=bright red/pink
Van Gieson
connective tissue method, collagen= red
nuclei= blue
cytoplasm= yellow
Giemsa
stains blood cells and other cell smears, nuclei dark blue, cytoplasm pale blue
Sudan Black & Osmium
stains lipid containing structures such as myelin brown/black
