histopathologic Flashcards
the first and most critical step
fixation
procedure whereby calcium or lime salts are removed from the tissues following fixation
decalcification
should be done after fixation and before impregnation
decalcification
the commonly used decalcifying agent
nitric acid
process in which it removes fixative and water from the tissue
dehydration
types of dehydrating agents:
ethanol, methanol, acetone
it involves removal of dehydrating agent and replacement by some fluid
clearing (de-alcoholization)
the clearing agent is completely removed from the tissues and replaced by a medium such as agar, gelatin, or wax
wax impregnation/infiltration
types of tissue impregnation and embedding media:
paraffin wax, celloidin, gelatin, plastic
ways of paraffin wax impregnation:
manual and automatic processing, vacuum embedding
the process by which the tissue is placed into a mold containing the embedding medium
blocking/embedding
cutting the excess wax from the block to expose the tissue surface in preparation for actual cutting
trimming
a process whereby tissues are cut into uniformly thin slices or sections with the aid of a machine, to facilitate the studies under the microscope
section-cutting
a specialized precision cutting instrument which accurately and repeatedly slices sections from a block of embedded tissue
microtome
used to preserve frozen tissue samples, slice tissue sections thin enough for microscopic examination
cryostat
provides a quick diagnosis for a variety of diseases and medical conditions
cryostat
a section is selected for staining and picked up onto a clean slide in a vertical position
floating out
the slides are placed on the hot plate adjusted at melting point of wax for 5 minutes
drying sections
process of applying dyes on the sections to see and study the architectural pattern of the tissue and physical characteristics of the cells
staining
the most common method utilized for microanatomical studies of tissues using the regressive staining
routine hematoxylin and eosin
done to preserve and support a stained section for microscopic examination
mounting
final step in tissue processing
labelling
occurs when tissue sections fail to spread properly
folds
caused by defects in the microtome knife
knife marks
tissue may be subjected to excessive pressure, tension or shrinkage during processing resulting in separations of tissue
separation
solution accumulate precipitate that may stick to the surface tissue section during staining procedure
stain precipitates
