histopath Flashcards
Preserve tissues permanently in as life-like a state as possible
Fixation
five major groups of fixatives
Aldehydes
Mercurials
Alcohols
Oxidizing agent
Picrates
Aldehydes include
Formaldehyde (formalin)
Glutaraldehyde
Tissue is fixed by cross linkages formed in the proteins, particularly between Lysine residues
Aldehydes
is good for immunohistochemical techniques
Formaldehyde
The standard solution for aldehyde
10% neutral buffered formalin
Causes deformation of alpha-helix structure in proteins so is not good for immunohistochemical staining
Glutaraldehyde
is good for electron microscopy
Glutaraldehyde
The standard solution for glutaraldehyde
2% buffered glutaraldehyde
Fix tissue by an unknown mechanism
Mercurials
for fixation of hematopoietic and reticuloendothelial tissues
Mercurials
Mercurial contains
mercuric chloride
B-5
Zenker’s
Alcohols contains
Methyl alcohol (methanol)
Ethyl alcohol (ethanol)
Protein denaturants and are not used routinely for tissues because they cause too much brittleness and hardness
Alcohols
very good for cytologic smears because they act quickly and give good nuclear detail
Alcohol
oxidizing agents
- permanganate fixatives (potassium permanganate)
- dichromate fixatives (potassium dichromate)
- osmium tetroxide
They cross-link proteins, but cause extensive denaturation
oxidizing agents
Used very infrequently
oxidizing agents
Fixatives with picric acid
picrates
Does almost as well as mercurials with nuclear detail but does not cause as much hardness
Picrates
surgical pathology and autopsy
formalin
surgical pathology and autopsy
formalin
for reticuloendothelial tissues (lymph nodes, spleen, bone marrow
zenkers
for testis, GI tract and endocrine tissue
bouins
Melted paraffin wax is
hydrophobic
popular clearing agent
xylene
Paraffin wax is miscible with xylene as well as
ispropanol
Most common paraffins have a melting point between ____ and the paraffin is typically kept at above melting point on the processor
55-58 C
2-4 C
is the removal of excess paraffin wax that is sitting around the tissue, which exposes the tissue in order to be sectioned.
coarse trimming