Small group 1 Flashcards
How can histology be defined?
Histology is the study of microscopic structures
What are the steps to tissue preparation?
- Fixation
- dehydration
- Embedding
- sectioning
- staining
What is fixation and why is it done?
This is the process that preserves histological sections
The goal is to preserve tissues as closely to the natural state as possible.
why?
- maintain cell and tissue morphology
- prevent decay
- terminates biochemical reactions
- crosslinks proteins
- kills microorganisms
How would a tissue be fixated for a light microscope?
formaldehyde or formalin (37% aqueous solution of Fa)
how would a tissue be fixed for an electron microscope?
glutaraldehyde (primary)
osmium tetroxide (secondary) for lipids!
How are tissues dehydrated?
A series of alcohol solutions of concentrations beginning at 10% and gradually increasing
How would embedding be done if using a light microscope?
paraffin
How would embedding be done if using an electron microscope?
epoxy resin
How should a tissue be sectioned for a light microscope?
5 - 15 micrometers thick
How should a tissue be sectioned for an EM
0.05 - 0.09 micrometers thick
Explain the hematoxylin and Eosin stain?
hematoxylin is a basic positive dye that normally reacts with the nucleus
The stain is blue in color
Eosin is an acidic dye that has a net negative charge that normally interacts with the cytoplasm.
The stain is pink in color
does not stain lipids well
Explain Mallory’s trichrome stain
aniline blue, acid fuchsin, and orange G
stains connective tissue
Masson’s Trichrome stain
smooth muscle will be stained red and connective tissue will be stained blue/green
What dyes stain lipids well?
oil red O
osmium tetroxide
sudan black
Explain what the silver stain does?
will stain reticular fibers black
H&E will not stain fibers
