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4 basic tissue types
epithelial, connective, muscular, neural CMEN (see mens tissue) TERM 2
why use microscopes to study histology?
DEFINITION 2 small size of matrix components and cells makes histology dependent on the use of microscopes TERM 3
Three sets of lenses for microscope
DEFINITION 3 a condenser (collects and focuses light), a set of objectives (enlarge and project image), and either one or two eyepieces (10x magnification) TERM 4
fixative solutions
DEFINITION 4 cross-link proteins, inactivating degradative enzymes (autolysis) and preserving cell structuresuse formalin (formaldehyde) TERM 5
dehydration
DEFINITION 5 fixed tissue istransferred through a series of increasingly more concentrated alcohol solutions, ending in 100% which effectively removes all wateruse ethanol
Steps for tissue preparation
1.Biopsy or organ dissection of tissue 2.Fixation (apolysis) use formaldehyde 3.Dehydrate cells in ethanol 4.Add clearing solution (paraffin goes in the holes where the water was in the cells) 1.Makes the tissue solid 5.The paraffin block is then cut with microtome 6.Deparaffin and stain TERM 7
clearing solution
DEFINITION 7 The alcohol is removedethanol is replaced with a solvent miscible with alcohol and embedding medium, and become transparent TERM 8
paraffin
DEFINITION 8 melted at 58C the tissue becomes completely infiltrated with this wax TERM 9
embedding
DEFINITION 9 After infiltration the tissue is placed in a small mold containing melted paraffin, which is then allowed to harden and become rigid TERM 10
slicing
DEFINITION 10 paraffin block is trimmed using a microtome to expose the tissue and then are floated in water
knife-mark artifact
caused either by a nick in the cutting edge of the knife or by an accumulation of debris just behind the cutting surface TERM 17
Physical fixation
DEFINITION 17 produced by a cryostat (freezing microtome) in which rapid freezing produces physical fixation of tissues that are ready for sectioningused for surgery when diagnosis is unknown or to see margin of legionvery fast, 10 mins TERM 18
Basophilic stains
DEFINITION 18 Tissues with a net negative charge (anionic) stain more readily with basic dyes (such as nucleic acids, cartilage matrix)Blue Hematoxylin, alcian blue, methylene blue TERM 19
Acidophilic Stains
DEFINITION 19 Tissues with a net positive charge (cationic), such as proteins, have an affinity for acidic dyespink (orange/red)Eosin, acid fuchsin, orange G TERM 20
counterstain
DEFINITION 20 stain other parts of the tissue normally not visible(background)
H&E
The combination of hematoxylin and eosin (H&E) stain is used most commonlybasophilic cell nuclei are stained blue- purple while cytoplasm stains pink TERM 22
Trichrome stains
DEFINITION 22 Three-colour staining Examples are Masson and Mallory stains distinguish extracellular tissue components better than H&E Suited for distinguishing cells from surrounding connective tissue TERM 23
Metachromasia
DEFINITION 23 characteristic change in the color of staining in biological tissues, exhibited by certain aniline dyes For example, toluidine blue becomes pink when bound to cartilage TERM 24
orthochromasia
DEFINITION 24 The absence of color change in staining is named TERM 25
Silver staining
DEFINITION 25 show proteinsvery sensitive and can show low levels of protein
Immunohistochemistry
A highly specific interaction between antigen and antibody The antibody is taggedMany pathologic conditions are diagnosed by localizing specific markers using antibodies TERM 32
Hybridization
DEFINITION 32 The binding of two single strands of nucleic acidsWhen a solution of nucleic acid is applied directly to cells or tissue sections it is called in situ hybridization TERM 33
FISH
DEFINITION 33 FISH (fluorescence in situ hybridization) is used to detect and localize the presence or absence of specific DNA sequences on chromosomes
