Introduction Flashcards
what is histopathology
studying tissues affected by disease
what is cytopathology
studying disaggregated cells
give example of how histological samples can be taken
biopsies, skin lesions, endoscopic biopsies
how can cells be taken for cytological samples
collect cells from urine and sputum, use needles to get cells from breast, thyroid and salivary glands
why is histology often therapeutic as well of diagnostic
you can cut out whole pieces of cancerous tissue
true of false: cytology is better for immunohistochemical molecular testing
false
what is cytology used for
to confirm the presence or absence of a cancer or dysplasia not to diagnose it
true of false: cytology is non or minimally invasive and safe
true
true or false cytology is faster and cheaper
true
what does metastasis means
cancer that has spread from another site
what is autolysis
self digestion of tissue which occurs when the blood supply is cut off
how can you block autolysis
fixatives
what do fixatives do
inactivate enzymes, denature proteins, prevent bacterial growth and harden tissue
what is used to fix cells
formalin
what must be done in order to thinly slice tissue samples
the tissue must be surrounded and impregnated with paraffin wax
what must happen before a tissue is impregnated with paraffin wax
water must be removed from the tissue using alcohol in a vacuum
when dehydrating cells what is the alcohol replaced with
xylene
in what machine does the embedding of tissue samples into paraffin wax occur in
processors
what happens when the tissue is taken out of a processor
it is put into a metal block which is filled with molten paraffin wax
what machine cuts the tissue into very small slices
microtome
how thin are the slices cut by microtome
3-4microns
what are tissues stained with
haematoxylin and eosin
what part of the cell does haematoxylin stain
the nuclei purple
what part of the cell does eosin stain
the cytoplasm and connective tissue pink
how is the slice of tissue preserved after staining `
attaching a coverslip on the top
what is immunohistochemistry
demonstration of substance on cells by labelling them with specific antibodies
in immunohistochemistry what is the antibody usually joined to
an enzyme such as peroxidase which catalyses a colour change
what are cytokeratins
fibrous proteins found in epithelia
what are frozen sections
method of hardening tissue quickly
how long does it take to prepare a slide by frozen section
10 minutes
when are frozen sections used
during an operation
what machine is used in frozen sections
cryostat
