Routine Paraffin Processing
Specimens received into the laboratory for paraffin processing, generally have already been fixed, usually with 10% neutral buffered formalin. These specimens must be processed to obtain paraffin sections for microscopic evaluation. The specimens are processed on an automatic tissue processor where there are fluid exchanges which gradually dehydrate and clear the tissues making them compatible to infiltration with molten paraffin. Then the specimens are embedded with molten paraffin in appropriately sized molds which are allowed to solidify into blocks.
These blocks are subsequently sectioned using a microtome to obtain 3-4 micron sections which are placed on glass microscope slides for future staining. In routinely processed material the prepared slides are generally stained with hematoxylin and eosin (H&E. Any stains other than H&E must be specifically requested. When the desired stains are completed the slides are coverslipped with a permanent mounting medium, labeled and returned to the requesting party.