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Histology > CHAPTER 1 (Book) > Flashcards

CHAPTER 1 (Book) Flashcards

Histology and its Methods of Study

1
Q

the study of the tissues of the body and
how these tissues are arranged to constitute organs.

A

Histology

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2
Q

Tissues have two interacting components:

A

cells and extracellular matrix (ECM)

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3
Q

supports the cells and contains the fluid transporting nutrients to the cells, and carrying away their wastes and secretory products

A

ECM

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4
Q

The most common procedure used in histologic research is the

A

preparation of tissue slices or “sections”

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5
Q

To preserve tissue structure and prevent degradation by enzymes released from the cells or microorganisms, pieces of organs are placed as soon as possible after removal from the body in solutions of stabilizing or cross-linking compounds called

A

fixatives

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6
Q

To improve cell preservation in large organs, fixatives are often introduced via

A

blood vessels with vascular perfusion

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7
Q

One widely used fixative for light microscopy is

A

formalin, a buffered isotonic solution of 37% formaldehyde

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8
Q

a fixative used for electron microscopy

A

glutaraldehyde

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9
Q

Electron microscopy provides much greater magnification and resolution of very small cellular structures, and fixation must be done very carefully to preserve additional “ultrastructural” detail. Typically in such studies, glutaraldehyde-treated tissue is then immersed in buffered

A

osmium tetroxide

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10
Q

osmium tetroxide, preserves and stains what?

A

cellular lipids as well as proteins

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11
Q

To permit thin sectioning, fixed tissues are

A

infiltrated and embedded

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12
Q

Embedding materials include

A

paraffin, plastic resins

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13
Q

Before infiltration with such media, the fixed tissue must undergo

A

dehydration

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14
Q

dehydration is done by having the tissues’ water extracted gradually by transfers through

A

a series of increasing ethanol solutions, ending in 100% ethanol

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15
Q

The ethanol is then replaced by an organic solvent miscible with both alcohol and the embedding medium, a step referred to as

A

clearing

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16
Q

The fully cleared tissue is then placed in melted paraffin in an oven at

A

52°-60°C

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17
Q

The hardened block with tissue and surrounding embedding medium is trimmed and placed for sectioning in an instrument called a

A

microtome

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18
Q

Paraffin sections are typically cut at _______ thickness for light microscopy

A

3-10 μm

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19
Q

electron microscopy requires sections that are

A

less than 1 μm thick.

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20
Q

are tissue samples removed during surgery or routine medical procedures.

A

Biopsies

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21
Q

If results of such analyses are required before the medical procedure is completed, for example to know whether a growth is malignant before the patient is closed, a much more rapid processing method is used called a

A

Frozen section

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22
Q

What medium is used in frozen section

A

liquid nitrogen

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23
Q

What microtome is used in a frozen section

A

cryostat in a cabinet at subfreezing temperature

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24
Q

Freezing of tissues is also effective in

A

histochemical studies, study of lipids

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25
Q

Most cells and extracellular material are completely colorless, and to be studied microscopically tissue sections must be

A

stained

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26
Q

nucleic acids has what charge

A

net negative (anionic)

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27
Q

proteins with many ionized amino groups has what charge

A

net positive (cationic)

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28
Q

Cell components, such as nucleic acids with a net negative charge (anionic), have an affinity for basic dyes and are termed

A

basophilic

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29
Q

cationic components, such as proteins with many ionized amino groups, stain more readily with acidic dyes and are termed

A

acidophilic

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30
Q

Examples of basic dyes include

A

toluidine blue, alcian blue, and methylene blue.

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31
Q

behaves like a basic dye, staining basophilic tissue components

A

Hematoxylin

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32
Q

The main tissue components that ionize and react with basic dyes do so because of acids in their composition

A

DNA, RNA, and glycosaminoglycans

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33
Q

Acid dyes includes

A

eg, eosin, orange G, and acid fuchsin

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34
Q

Acid dyes (eg, eosin, orange G, and acid fuchsin) stain the acidophilic components of tissues such as

A

mitochondria, secretory granules, and collagen

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35
Q

Of all staining methods, the simple combination of is used most commonly

A

hematoxylin and eosin (H&E)

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36
Q

Hematoxylin stains

A

DNA in the cell nucleus, RNA-rich portions of the cytoplasm, and the matrix of cartilage

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37
Q

eosin stains

A

other cytoplasmic structures and collagen

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38
Q

Here eosin is considered a

A

counterstain

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39
Q

More complex procedures, such as__________, allow greater distinctions among various extracellular tissue components.

A

trichrome stains (eg, Masson’s trichrome)

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40
Q

utilizes the hexose rings of polysaccharides and other carbohydrate-rich tissue structures and stains such macromolecules distinctly purple or magenta

A

periodic acid–Schiff (PAS) reaction

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41
Q

The DNA of cell nuclei can be specifically stained using a modification of the PAS procedure called the

A

Feulgen reaction

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42
Q

Basophilic or PAS-positive material can be further identified by

A

enzyme digestion

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43
Q

Examining lipids are stained by?

A

lipid-soluble dyes such as Sudan black

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44
Q

Less common methods of staining can employ

A

metal impregnation

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45
Q

typically using solutions of silver salts to visual certain ECM fibers and specific cellular elements in nervous tissue.

A

metal impregnation techniques

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46
Q

Slide preparation, from tissue fixation to observation with a light microscope, may take from

A

12 hours to 2½ days

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47
Q

Small pieces of tissue are placed in solutions of chemicals that cross-link proteins and inactivate degradative enzymes, which preserve cell and tissue structure

A

Fixation

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48
Q

The tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%, which removes all water.

A

Dehydration

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49
Q

Alcohol is removed in organic solvents in which both alcohol and paraffin are miscible

A

Clearing

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50
Q

The tissue is then placed in melted paraffin until it becomes completely infiltrated with this substance.

A

Infiltration

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51
Q

The paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden

A

Embedding

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52
Q

The resulting paraffin block is trimmed to expose the tissue for sectioning (slicing) on a microtome.

A

Trimming

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53
Q

Similar steps are used in preparing tissue for transmission electron microscopy (TEM), except special fixatives and dehydrating solutions are used with smaller tissue samples and embedding involves _______ which become harder than paraffin to allow very thin sectioning.

A

epoxy resins

54
Q

With _________ stained tissue is examined with ordinary light passing through the preparation

A

bright-field microscope

55
Q

highly sensitive to low light levels with a camera and monitor used to view the microscope

A

charge-coupled device (CCD)

56
Q

The critical factor in obtaining a crisp, detailed image with a light microscope is its

A

resolving power

57
Q

defined as the smallest distance between two structures at which they can be seen as separate objects

A

resolving power

58
Q

The maximal resolving power of the
light microscope is approximately

A

0.2 μm

59
Q

Objects smaller or thinner than 0.2 μm such cannot be distinguished with light microscope

A

as a single ribosome or cytoplasmic
microfilament

60
Q

typically used for study of brightfield
microscopic preparations, involves the conversion of a stained tissue preparation to high-resolution digital images and permits study of tissues using a computer or other digital device,

A

Virtual microscopy

61
Q

In virtual microscopy regions of a glass-mounted specimen are captured digitally in a grid-like pattern at multiple magnifications using a

A

specialized slide-scanning microscope

62
Q

When certain cellular substances are irradiated by light of a proper wavelength, they emit light with a longer wavelength—a phenomenon called

A

fluorescence

63
Q

In _______ tissue sections are usually irradiated with ultraviolet (UV) light and the emission is in the visible portion of the spectrum before analyzing

A

fluorescence microscopy

64
Q

Fluorescent compounds with affinity for specific cell macromolecules may be used as fluorescent stains. _____________ which binds both DNA and RNA, is an example

A

Acridine orange

65
Q

Other compounds, such as _____________ stain specifically bind DNA and are used to stain cell nuclei, emitting a characteristic blue fluorescence under UV

A

DAPI and Hoechst

66
Q

Another important application of fluorescence microscopy is achieved by coupling compounds such as __________________to molecules that will specifically bind to certain cellular components and thus allow the identification of these structures under the microscope

A

fluorescein

67
Q

Unstained cells and tissue sections, which are usually transparent and colorless, can be studied with these modified light microscopes

A

Phase-Contrast Microscopy

68
Q

A modification of phase-contrast microscopy is

A

differential interference contrast microscopy

69
Q

differential interference contrast microscopy produces what images

A

image of living cells with a more apparent three-dimensional (3D) aspect

70
Q

DAPI

A

4′,6-diamino-2-phenylindole

71
Q

binds actin filaments green

A

fluorescein phalloidin

72
Q

avoids problems found in bright field microscopes and achieves high resolution and sharp focus by using (1) a small point of high-intensity light, often from a laser and (2) a plate with a pinhole aperture in front of the image detector

A

Confocal microscopy

73
Q

Confocal microscopy avoids problems found in bright field microscopes and achieves high resolution and sharp focus by using

A

(1) a small point of high-intensity light, often from a laser

(2) a plate with a pinhole aperture in front of the image detector

74
Q

allows the recognition of stained or unstained structures made of highly organized subunits

A

Polarizing microscopy

75
Q

The ability to rotate the direction of vibration of polarized light is called

A

birefringence

76
Q

are based on the interaction of tissue components with beams of electrons

A

Transmission and scanning electron microscopes

77
Q

is an imaging system that permits resolution around 3 nm

A

transmission electron microscope (TEM)

78
Q

The transmission electron microscope (TEM) is an imaging system that permits resolution around 3 nm. This high resolution allows isolated particles magnified as much as

A

400,000 times to be viewed in detail

79
Q

Specimens typically studied by TEM

A

Very thin (40-90 nm), resin-embedded tissue sections

80
Q

parts of Transmission electron microscope

A

Cathode
Anode
Condensor lens
Objective lens
Intermediate lens
Projector lens
Image on viewing screen
Electron detector with CCD camera
Electron gun
Copper grid with 3 sections (3nm)
Specimen holder
Column
TEM image

81
Q

Parts of Scanning electron microscope

A

Cathode
Anode
Lens
Lens #2
Scanner
Lens #3
Specimen
Electron gun
Column
Electron detector
SEM image

82
Q

To improve contrast and resolution in TEM, compounds with _________ are often added to the fixative or dehydrating solutions used for tissue preparation.

A

heavy metal ions

83
Q

Examples of heavy metal ions used in tissue preparation for TEM

A

osmium tetroxide, lead citrate, and uranyl compounds

84
Q

are techniques that allow TEM study of cells without fixation or embedding and have been particularly useful in the study of membrane structure

A

Cryofracture and freeze etching

85
Q

In cryofracture and freeze etching, a replica of the frozen exposed surface of the specimen is produced in a vacuum by applying thin coats of

A

vaporized platinum or other metal atoms

86
Q

provides a high-resolution view of the surfaces of cells, tissues, and organs. Like the TEM, this microscope produces and focuses a very narrow beam of electrons, but in this instrument the beam does not pass through the specimen

A

Scanning electron microscopy (SEM)

87
Q

Often used heavy metal in SEM

A

gold

88
Q

is a method of localizing newly synthesized macromolecules in cells or tissue sections.

A

Microscopic autoradiography

89
Q

act as microdetectors of the radiation in the same way that they respond to light in photographic film in samples with radiolabeled cells or tissue sections

A

silver bromide crystals

90
Q

Much histological information becomes available by autoradiography. If a radioactive precursor of DNA such as_____________ is used, it is possible to know which cells in a tissue and how many are replicating DNA

A

tritium-labeled thymidine

91
Q

Autoradiographs are tissue preparations in which particles called ________ indicate the cells or regions of cells in which specific macromolecules were synthesized just prior to fixation.

A

silver grains

92
Q

Live cells and tissues can be maintained and studied outside the body in culture

A

in vitro

93
Q

Live cells and tissues can be maintained and studied in the organism, cells are bathed in fluid derived from blood plasma and containing many different molecules required for survival and growth

A

in vivo

94
Q

primary cell cultures steps

A
  1. cells and tissues are GROWN in complex solutions of known composition (salts, amino acids, vitamins)
  2. serum or specific growth factors are ADDED
  3. Cells to be cultured are DISPERSED mechanically or enzymatically from a tissue or organ
  4. PLACED with sterile procedures in a clear dish to which they adhere
95
Q

Some cells can be maintained in vitro for long periods because they become immortalized and constitute a permanent

A

cell line

96
Q

Most cells obtained from normal tissues have a finite, genetically programmed life span. However, certain changes can promote cell immortality, a process called

A

transformation

97
Q

Cervical cancer cells from a patient later identified as Henrietta Lacks, who died from the disease in 1951, were used to establish one of the first cell lines, called

A

HeLa cells

98
Q

HeLa cells are used to study the potential treatment benefits of a drug called ______ against certain blood cancers and sickle cell anemia.

A

Hydroxyurea

99
Q

is a method for localizing cellular structures using a specific enzymatic activity present in those structures

A

Enzyme histochemistry (or cytochemistry)

100
Q

To preserve the endogenous enzymes, histochemical procedures usually use

A

unfixed or mildly fixed tissue

101
Q

For enzyme histochemistry tissue preparation is done by:

A

(1) tissue sections are
immersed in a solution containing the substrate of the enzyme
to be localized

(2) the enzyme is allowed to act on its substrate

(3) the section is then put in contact with a marker compound that reacts with a product of the enzymatic action on the substrate

(4) the final product from the marker, which must be insoluble and visible by light or electron microscopy, precipitates over the site of the enzymes, identifying their location.

102
Q

Examples of enzymes that can be detected histochemically include the following:

A

Phosphatases
Dehydrogenases
Peroxidase

103
Q

used to diagnose the iron storage diseases, hemochromatosis and hemosiderosis

A

Perls’ Prussian blue reaction for iron

104
Q

to detect glycogenosis and mucopolysaccharidosis

A

PAS-amylase and alcian blue
reactions for polysaccharides

105
Q

to detect sphingolipidosis

A

reactions for lipids and sphingolipids

106
Q

The most commonly used labels are

A

fluorescent compounds
radioactive atoms
peroxidase or other enzymes (histochemistry)
metal (usually gold)

107
Q

Examples of molecules that interact specifically with other molecules include the following (visualizing specific molecules)

A

Phalloidin
Protein A
Lectins

108
Q

(visualizing specific molecules) glycoproteins derived mainly from plant seeds, bind to carbohydrates with high affinity and specificity

A

Lectins

109
Q

(visualizing specific molecules) purified from Staphylococcus aureus bacteria, binds to the Fc region of antibody molecules, and can therefore be used to localize naturally occurring or applied antibodies bound to cell structures

A

Protein A

110
Q

(visualizing specific molecules) a compound extracted from mushroom, Amanita phalloides, interacts strongly with the actin protein of microfilaments.

A

Phalloidin

111
Q

labeled antibodies are routinely used in _____________ to identify and localize many specific proteins, not just those with enzymatic activity that can be demonstrated by histochemistry.

A

immunohistochemistry

112
Q

Widely applied for both research and diagnostic purposes, every immunohistochemical technique requires an antibody against the protein that is to be detected. This means that the protein must have been previously purified using

A

biochemical or molecular methods

113
Q

Growth and activity of activated lymphocytes can be prolonged indefinitely by fusing them with ____________ to produce _________

A

lymphocytic tumor cells

hybridoma cells

114
Q

Antibodies are commonly tagged
with fluorescent compounds, with __________ for histochemical detection

A

peroxidase or alkaline
phosphatase

115
Q

There are other indirect methods that involve the use of other intermediate molecules, such as the__________ technique, which are also used to amplify detection signals.

A

biotin-avidin

116
Q

usually implies the specific binding between
two single strands of nucleic acid, which occurs under appropriate conditions if the strands are complementary

A

Hybridization

117
Q

A single cultured uterine cell stained fluorescently to reveal a meshwork of intermediate filaments (green) throughout
the cytoplasm. Primary antibodies against the filament protein__________ were used in the indirect staining technique, with the nucleus counterstained blue with DAPI. (X650)

A

desmin and fluorescein isothiocyanate (FITC)-labeled secondary antibodies

118
Q

DAB

A

3,3′-diamino-azobenzidine

119
Q

Examples of specific antigens with diagnostic importance.

Specific cytokeratins

A

Tumors of epithelial origin

120
Q

Examples of specific antigens with diagnostic importance.

Protein and polypeptide hormones

A

Certain endocrine tumors

121
Q

Examples of specific antigens with diagnostic importance.

Carcinoembryonic antigen (CEA)

A

Glandular tumors, mainly of the digestive tract and breast

122
Q

Examples of specific antigens with diagnostic importance.

Steroid hormone receptors

A

Breast duct cell tumors

123
Q

Examples of specific antigens with diagnostic importance.

Antigens produced by viruses

A

Specific virus infections

124
Q

Hybridization at stringent conditions allows the specific identification of sequences in genes or RNA. This can occur with cellular DNA or RNA when nucleic acid sequences
in solution are applied directly to prepared cells and tissue sections, a procedure called

A

in situ hybridization (ISH)

125
Q

in situ hybridization (ISH) is ideal for?

A

determining if a cell has
a specific sequence of DNA

identifying the cells containing specific messenger RNAs (mRNAs)

determining the localization of a gene
in a specific chromosome

126
Q

in ISH the nucleotide sequences of interest are detected with

A

probes

127
Q

probes consists of?

A

single-stranded complementary
DNA (cDNA)

128
Q

The probe may be obtained by

A

cloning by polymerase chain reaction (PCR) amplification of the target sequence

or by chemical synthesis

129
Q

The probe is tagged with nucleotides containing a radioactive isotope (localized by autoradiography) or modified with
a small compound such as

A

digoxigenin

130
Q

Certain steps in tissue procedure may distort the tissues slightly, producing minor structural abnormalities called

A

artifacts

Histology (15 decks)

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