tissue processing Flashcards
goal of tissue processing
remove all water from a specimen, and replace it with an inert stable material
what are the three steps of removing and replacing water
- dehydration
- clearing
- infiltration
dehydration
- remove water and replace with material miscible with clearing agent
- must be performed slowly and gently
- accomplished by increasing concentrations of alcohol
what happens to the tissue of dehydration is incomplete
tissue will be soft and mushy
what happens if dehydration is too long
tissue will become hard and brittle
clearing
remove dehydrating agent and replace with material miscible with infiltrating agent
what happens if clearing portion is inadequate or prolonged
same as dehydration but has a more greasy feeling
infiltration
removes clearing agent and replaces with inert, stable, supportive material
- provides internal support to tissues for cutting and further manipulation
- longest step
- most often accomplished with paraffin was with or without additives
- paraffin wax chosen based on individual needs of lab
rate of tissue processing
slow as fuck
what to do if there is an error
any missed step in processing can be corrected to some degree
- if specimens not fixed before processing there is irreparable damage
* move through each step backwards until step with error, then move forwards to the end
maintenance of solutions
replace all single solutions with new
dirtiest version of repeat is replaces and shifted to end position in step, and others shifted up one place
- occurs after every run
what are some outcomes after processing
tissue is about 60% its og size
more brittle
lipids are dissolved away, except for those tightly bound like myelin sheath
what can you do if there is a STAT
microwave processing
- substantially faster
- though it is much more finicky
- suitable for one sample at a time
