Histology and it's Methods of Study Flashcards
preserve tissue structure and prevent degradation
fixation
examples of fixatives
formalin
glutaraldehyde
examples of fixatives
used in light microscopy
formalin
examples of fixatives
used in electron microscopy
glutaraldehyde
removes cell water and fixative by using series of alcohol solutions
dehydration
alcohol is removed from the tissue using a cleaning agent
clearing
popular clearing agent
xylene
paraffin-infiltrated tissue is placed in a small mold
embedding
done to obtain a rigid consistency of the specimen for sectioning
embedding
paraffin block trimmed to expose the tissue for sectioning (slicing) on a microtome
trimming
applying dyes on sections aids in the visualization of the architectural pattern of tissues and their physical characteristics and the relationship of cells and extracellular materials
staining
stains DNA in the cell nucleus; purplish blue
hematoxylin
stains cytoplasmic structures; used as a counterstain; red or pink
eosin
uses the hexose rings of POLYSACCHARIDES and other carbohydrate-ruch tissue structures; purple or magenta
periodic acid-schiff
lipid-soluble dye
“lipid-rich structures of cells are revealed by avoiding the processing steps that remove lipids, such as the processing steps that remove lipids, such as treatment with heat and organic solvents
sudan black
utilizes solutions of silver salts to visualize extracellular matrix fibers and cellular elements in nervous tissue
metal impregnation
conventional bright-field microscopy, including the fluorescence, phase-contrast, confocal, and polarizing microscopy, are all based on the INTERACTION OF LIGHT with tissue components and are used to REVEAL AND STUDY TISSUE FEATURES
light microscopy
collects and focuses a cone of light that illuminates the tissue slide on the stage
condenser
lenses enlarge and project the illuminated image of the object toward the eyepiece
objective
magnify this image another X10 and project it to the viewer, yeilding a total magnification of X40, X100, X400
eyepieces
uses ULTRAVIOLET LIGHT, under which ONLY FLUORESCENT MOLECULES ARE VISIBLE, allowing localization of fluorescent probes which can be much more specific than routine stains
fluorescence microscopy
uses the difference in refractive index of various NATURAL CELL AND TISSUE COMPONENTS to produce an image without staining, allowing observation of living cells
phase-contrast microscopy
involves scanning the specimen at successive focal planes with a focused light beam, often from a laser, and produces a 3D RECONSTRUCTION from the images obtained
confocal microscopy
allows the recognition of stained or unstained structures made of highly organized subunits
polarizing microscopy
techniques use SPECIFIC ENZYMATIC ACTIVITIES IN LIGHTLY OR UNFIXED TISSUE SECTIONS to produce visible products in the specific enzyme locations
enzyme histochemistry
based on SPECIFIC REACTIONS BETWEEN AN ANTIGEN AND ANTIBODIES labeled with visible markers, often fluorescent compounds or peroxidase for light microscopy, and gold particles for transmission electron microscope
immunohistochemistry
specific gene sequences or mRNAs of cells can be detected microscopically using LABELLED COMPLEMENTARY DNA PROBES in ISH
in situ hybridization
Many steps in tissue processing, slide preparation, and staining can introduce minor ARTIFACTS such as spaces and precipitates that are not normally present in the living tissue and must be recognized
interpretation of structures in tissue section
