Histology and Cytology Flashcards
(32 cards)
what is histology
the study of the microscopic structure of tissues.
what is cytology
the study of cells
what is fixation
fixation is the first step in tissue processing
the specimen is often recieved in fixation
10-20 times fixative to tissue ratio
refrigerate at 4 degrees until sliced
Advantages and Disadvantages of formalin
left in there for a long time without damage - but irritating vapor which burns eyes and damages mucus membranes
what is grossing
the speicmnet is examined in thin 3-5 mm slices and placed in the tissue cassetee
what is decalcification
tissue containing calium salts is calcified and is difficult to cut - using a decalcifying adject like formic acid ROD Edta and Van Ebners Fluid
what us dehydration
the controlled removal of water using ethonal - decending to ascending grades of alcohool
what is clearing
the removal of the dehydration agent and replacing it with a reagent which is a solvent of paraffin wax
what is wax impregnation or infiltration
the clearing agent in the tissue is replaced with molten parafinnin wax
what is embedding
the embedding center has a hot portion to hold the tissue cassettes
what is a microtomy
tissue place placed in a microtome and sectioned to 3-5 mm 40-45 degree water bath and then placed onto a labeled glass slide- the slide is dried to prevent section from falling off and is now ready for staining
Hematoxylin stains nuclei
blue/purple
Eosin stains cytoplasm:
pink
Tissue components stain:
pink/red
why cover slipping is important
to protect and preserve the stained tissue section and to allow it to be viewed under a microscope
10% formalin = how much formaldehyde
3.7-4 %
what is progressive vs Regressive stains
pro- occurs when the hematoxylin is added to the tissue without being followed by a differentiator to remove excess dye
reg- the tissue is deliberately overstained and then destained until proper endpoint
Equipment temp
paraffin 2-4 degrees above the melting point
flotation bath 5 degrees below the melting point
drying over 62 degrees for proper adherence and deparaffinization of tissue processes
what is a direct stain vs indirect stain
direct - cells can be stained or dyed
indirect - procedure colours background and cells colourless
What is Ripening
the oxidation product of hematoxylin is hematein
examples of modants
salts of aluminum
iron
tungsten
occasionally lead
what is a simple fixative
fixatievs that can be used alone
what is a compound fixation
combantion of fixtives
what are chelating agents
organic compounds that bind certain metals
