Overview Flashcards
What is the definition of pathology?
Study of disease
What is the definition of histology?
Study of body tissues.
What is the definition of histopathology?
Study of disease in body tissues and organs.
What is the definition of histotechnology?
All the technical steps taken to prepare tissue specimens for microscopic examination by a pathologist.
Surgical removal of tissue –>
examination of stained slides for diagnostic purposes.
What are the histotechnology steps?
- Specimen entry, gross description, and dissection.
- Fixation and if required decalcification.
- Processing –> includes dehydration, clearing, impregnation/infiltration
- Embedding
- Microtomy/sectioning
- Staining
What is the purpose of using fixatives?
Leaves the tissue in “as life-like state” as possible.
Prevents autolysis and putrefaction.
Important step - once damage is done to tissue it is irreversible.
Typically specimens are fixed for 24 hours.
What is the purpose of decalcification?
Bone specimens must be decalcified to remove calcium salts before they can be cut on a microtome. This is done before fixation and processing.
What is the main purpose of processing?
To be able to cut the tissue as thin as possible (one cell thick to 3um to 5um, need to be able to infiltrate tissue sample with paraffin to provide internal support for cutting thin sections.
Since water and wax don’t mix, you need to dehydrate with alcohols and clear with xylene before infiltrating the sample with paraffin wax.
What equipment is used for processing?
A lab instrument called a processor. See histo overview presentation for picture.
What is embedding and when is it done?
After wax is in the tissues, the tissue is embedded in a block of wax.
Why is staining done?
It is much easier to see cellular definition in a stained tissue.
What is the main stain used in Histopathology?
Hematoxylin and Eosin stain (H&E for short).
