quiz 9 Flashcards
the science of studying the cellular anatomy of tissues using a microscope
Histology
examine sections of biopsies from human tissues to evaluate disease progression, diagnose and classify cancers, and identify infectious diseases
pathologists
tissues are prepared by trained professionals called
histotechnologists or histotechnicians
When tissue is removed from an organism, it begins a process of ________. Cells undergo __________(self-lysis and destruction by the cells’ own enzymes,) proteins aggregate, and muscle cells become rigid.
decay, autolysis
To prevent decay, tissue is immediately placed in a ________ to preserve it.
fixative
Alcohols (including ethanol, methanol, and isopropanol,) acetic acid, and acetone may be included in fixatives because they _______________ the tissue.
rapidly penetrate
fixatives act by ___________ proteins and nucleic acids in cells, causing them to come out of solution and clump together
precipitating
come out of solution and clump together
precipitating
The precipitation process can damage the tissue and
create ____________, however. Artifacts are structures appearing in fixed tissue that are not present in the original living tissue.
artifacts
The precipitation process can damage the tissue and
create ____________, however. Artifacts are structures appearing in fixed tissue that are not present in the original living tissue.
artifacts
structures appearing in fixed tissue that are not present in the original living tissue.
Artifacts
other major class of fixatives consists of ___________ agents
crosslinking
crosslinking agent example
formaldehyde
work by creating covalent chemical bridges within and between protein and nucleic acid molecules
formaldehyde
Human and animal tissues are usually fixed in ________________, which is a pH-balanced sodium phosphate solution containing 4% formaldehyde.
10% neutral buffered formalin
Crosslinking retains more of the natural tissue structure and produces fewer artifacts than precipitation
T/F
T
After tissues are fixed, they must be prepared for _________________
sectioning
thin slices of the tissue are cut using a microtome, and the sections are adhered to a glass microscope slide
sectioning
To get very thin slices, the tissue must be embedded in a _____________after fixation to support it and prevent distortion from occurring
solid matrix
two major types of sections used in histology:
paraffin-embedded and frozen
embedded in paraffin by sequential immersion in alcohol solutions, xylene, and melted paraffin wax. This dehydrates the tissue and allows molten paraffin to infiltrate it. When the wax cools, a sturdy paraffin block with the tissue embedded inside is produced. The paraffin block is then
sliced into thin sections with the microtome
paraffin-embedded
To prepare frozen sections, tissue is placed in
cryoembedding medium and then rapidly frozen. Sections are prepared using a cryostat, which is a microtome mounted inside a refrigerated chamber that keeps the tissue at around -20°C.
frozen
Most tissues are transparent when viewed under the microscope
T/F
T
most common differential stain for animal tissues is
hematoxylin and eosin (H&E)
_____________ a basic (positively-charged) dye that binds to negatively charged molecules like DNA.
Hematoxylin is,
will stain nuclei a blue/purple color
Hematoxylin
___________ is an acidic (negatively-charged) dye that binds to
positively-charged molecules, including many proteins.
Eosin
_________ will stain the cytoplasm of cells pink.
Eosin
