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Basic Histology > Histology Ch.1 > Flashcards

Histology Ch.1 Flashcards

Histology & Its Methods of Study (75 cards)

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1
Q

What does histology explore?

A

The body’s tissues and their arrangement to produce functional organs

Histology involves cellular biology and microscopic anatomy focusing on cell activities and structures.

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2
Q

What are the two main components of tissues?

A

Cells and extracellular matrix (ECM)

The ECM includes macromolecules like collagen that support cells.

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3
Q

What is the role of the extracellular matrix (ECM)?

A

Supports cells and contains fluids for nutrient transport and waste removal

The ECM is produced by cells and influences their behavior.

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4
Q

What is the importance of microscopy in histology?

A

It allows examination of small cells and matrix components

Microscopy is essential for studying tissue biology.

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5
Q

What are the initial steps in tissue preparation for light microscopy?

A

Fixation, dehydration, clearing, infiltration, embedding, trimming

These steps ensure the tissue retains its structural features.

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6
Q

What is the purpose of fixation in tissue preparation?

A

To preserve tissue structure and prevent degradation

Fixatives like formalin are used to stabilize proteins.

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7
Q

What is a common fixative used for light microscopy?

A

Formalin

Formalin is a buffered isotonic solution of 37% formaldehyde.

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8
Q

What is the function of a microtome in histology?

A

To section paraffin-embedded tissues

A microtome cuts tissue blocks into thin sections for microscopic analysis.

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9
Q

What are the typical thicknesses for paraffin sections in light microscopy?

A

3–10 µm

Electron microscopy requires sections less than 1 µm thick.

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10
Q

What is the primary purpose of staining in histology?

A

To make tissue components visible and distinguishable

Staining is essential since most cells and materials are colorless.

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11
Q

What is the most common staining method used in histology?

A

Hematoxylin and eosin (H&E)

H&E provides contrast between different tissue components.

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12
Q

What does hematoxylin stain in tissue sections?

A

DNA in the cell nucleus and RNA-rich cytoplasm

Hematoxylin produces a dark blue or purplish color.

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13
Q

What type of structures does eosin stain?

A

Cytoplasmic structures and collagen

Eosin typically stains these components pink.

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14
Q

What is the periodic acid–Schiff (PAS) reaction used for?

A

To stain carbohydrate-rich tissue structures

PAS stains such macromolecules purple or magenta.

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15
Q

What is the total magnification achieved with a bright-field microscope using a ×10 ocular and a ×40 objective?

A

×400

Total magnification is the product of the objective and ocular lens magnifications.

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16
Q

What is the resolving power of a light microscope?

A

Approximately 0.2 µm

This defines the smallest distance between two structures that can be seen as separate.

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17
Q

How long does slide preparation typically take?

A

From 12 hours to 2½ days

Time varies based on tissue size, embedding medium, and staining method.

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18
Q

What is the role of lipid-soluble dyes in histology?

A

To stain lipid-rich structures in cells

Examples include Sudan black, useful for diagnosing metabolic diseases.

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19
Q

What is a cryostat used for?

A

To section frozen tissue for rapid microscopic examination

It allows quick analysis of biopsies during surgical procedures.

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20
Q

What is resolving power in microscopy?

A

The smallest distance between two structures at which they can be seen as separate objects.

The maximal resolving power of the light microscope is approximately 0.2 µm.

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21
Q

What is the maximum resolving power of a light microscope?

A

Approximately 0.2 µm.

This allows clear images magnified 1000–1500 times.

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22
Q

What happens to structures smaller than 0.2 µm in a light microscope?

A

They cannot be distinguished with this instrument.

Examples include a single ribosome or cytoplasmic microfilament.

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23
Q

How does magnification relate to resolution in microscopy?

A

Magnification is of value only when accompanied by high resolution.

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24
Q

What is virtual microscopy?

A

A technique that converts stained tissue preparations to high-resolution digital images for study without actual slides or microscopes.

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25
What are the advantages of virtual microscopy?
Cost-effective and ease of use. ## Footnote It is rapidly replacing light microscopes in histology laboratories.
26
What is fluorescence in microscopy?
A phenomenon where certain cellular substances emit light of a longer wavelength when irradiated by light of a proper wavelength.
27
What type of light is typically used in fluorescence microscopy?
Ultraviolet (UV) light.
28
What do fluorescent compounds do in microscopy?
They bind to specific cell macromolecules and allow identification of structures under the microscope.
29
Which fluorescent compounds are commonly used to stain DNA?
DAPI and Hoechst.
30
What is the principle of phase-contrast microscopy?
It produces visible images from transparent objects by using light changes in speed when passing through structures with different refractive indices.
31
What type of microscopy allows the study of live cells?
Phase-contrast microscopy.
32
What is confocal microscopy?
A microscopy technique that uses a small point of high-intensity light and a pinhole aperture to achieve high resolution and sharp focus.
33
What is the advantage of confocal microscopy over bright-field microscopy?
It avoids stray light that reduces contrast, allowing for greater precision in localization of specimen components.
34
What is birefringence in polarizing microscopy?
The ability to rotate the direction of vibration of polarized light, a feature of crystalline substances or highly oriented molecules.
35
What structures can be recognized using polarizing microscopy?
Structures made of highly organized subunits, such as cellulose, collagen, microtubules, and actin filaments.
36
What is the resolution capability of transmission electron microscopy (TEM)?
Around 3 nm.
37
What is the maximum magnification achievable with TEM?
Approximately 400,000 times.
38
What are the typical preparations for TEM?
Very thin (40–90 nm), resin-embedded tissue sections.
39
What is the purpose of heavy metal ions in TEM specimen preparation?
To improve contrast and resolution by increasing electron density.
40
How does scanning electron microscopy (SEM) differ from TEM?
SEM scans the surface of specimens and does not pass electrons through them.
41
What is the result of coating specimens in SEM?
Specimens are coated with metal to reflect electrons, producing a black-and-white image with a 3D quality.
42
What is autoradiography?
A method to localize newly synthesized macromolecules in cells or tissue sections using radioactively labeled metabolites.
43
What is autoradiography?
A method of localizing newly synthesized macromolecules in cells or tissue sections using radioactively labeled metabolites. ## Footnote Autoradiography helps visualize specific macromolecules like DNA, RNA, proteins, and glycoproteins by detecting radiation from incorporated isotopes.
44
What are the steps involved in autoradiography?
1. Provide radioactively labeled metabolites to cells 2. Fix and process tissue 3. Coat slides with photographic emulsion 4. Develop slides to visualize silver grains indicating labeled macromolecules. ## Footnote These steps enable the identification of specific cellular structures based on their synthesized macromolecules.
45
What does the presence of black grains in autoradiographs indicate?
The localization of specific macromolecules synthesized just prior to fixation. ## Footnote Black grains represent areas where radiolabeled precursors were incorporated into macromolecules.
46
What is the significance of using a radioactive precursor of DNA in autoradiography?
It allows identification of cells that are replicating DNA and preparing to divide. ## Footnote This method is useful for studying cellular proliferation.
47
What is cell culture?
The maintenance and study of live cells and tissues outside the body in vitro. ## Footnote Cell culture allows direct observation of cellular behavior and experimentation that isn't possible in vivo.
48
What is a primary cell culture?
A preparation where cells are dispersed from a tissue or organ and placed in a dish to grow as a single layer. ## Footnote Primary cultures can be established from various tissues for experimental purposes.
49
What is cell transformation?
The process that promotes cell immortality, similar to changes in normal cells becoming cancer cells. ## Footnote Transformation allows certain cells to be maintained indefinitely in culture.
50
What is enzyme histochemistry?
A method for localizing cellular structures using specific enzymatic activity present in those structures. ## Footnote This technique preserves endogenous enzymes and utilizes specific substrates to visualize enzyme activity.
51
What are some examples of enzymes that can be detected histochemically?
* Phosphatases * Dehydrogenases * Peroxidase ## Footnote These enzymes are crucial for various metabolic processes and their localization helps in understanding cellular functions.
52
What is the role of immunohistochemistry?
To identify and localize specific proteins using labeled antibodies against antigens. ## Footnote Immunohistochemistry is widely used for research and diagnostic purposes.
53
What is the difference between direct and indirect immunocytochemistry?
Direct uses a labeled antibody that binds the protein of interest, while indirect uses a primary antibody followed by a labeled secondary antibody. ## Footnote Indirect methods amplify the signal and increase sensitivity.
54
What is the significance of using monoclonal antibodies in immunohistochemistry?
They provide high specificity and strong binding to the target protein with less nonspecific binding. ## Footnote Monoclonal antibodies are produced from a single clone of lymphocytes and target a specific epitope.
55
Fill in the blank: Autoradiography allows researchers to track the _______ of proteins in cells.
[migration] ## Footnote This tracking can show the path and localization of proteins after synthesis.
56
True or False: Cell culture can only be performed with immortalized cells.
False ## Footnote Both primary and immortalized cells can be cultured, but immortalized cells can be maintained indefinitely.
57
What are HeLa cells?
One of the first established cell lines from cervical cancer cells of Henrietta Lacks, used worldwide in research. ## Footnote HeLa cells have contributed significantly to our understanding of cellular structure and function.
58
What is the purpose of using fluorescent compounds in immunohistochemistry?
To visualize the location of specific proteins when bound by antibodies. ## Footnote Fluorescent labeling allows for clear detection under light microscopy.
59
What is the role of lectins in visualizing specific molecules?
Lectins bind specifically to carbohydrates and can be used to stain glycoproteins or other macromolecules. ## Footnote This specificity helps identify the presence of certain sugars or sequences in tissues.
60
What fluorescent staining technique was used to reveal intermediate filaments in cultured uterine cells?
Primary antibodies against desmin and FITC-labeled secondary antibodies ## Footnote DAPI was used to counterstain the nucleus.
61
What enzyme was targeted in the small intestine section using an antibody?
Lysozyme ## Footnote The secondary antibody was labeled with peroxidase and visualized using DAB.
62
What is the role of protein A in the TEM preparation of pancreatic cells?
It has high affinity toward antibody molecules to reveal amylase with gold particles ## Footnote Gold particles appear as small black dots over secretory granules.
63
What is the purpose of immunohistochemistry in clinical practice?
To diagnose diseases by detecting unique proteins in cells ## Footnote This includes certain types of tumors and virus-infected cells.
64
What does hybridization imply in the context of nucleic acids?
Specific binding between two single strands of nucleic acid ## Footnote This occurs under appropriate conditions if the strands are complementary.
65
What is the technique called that determines if a cell has a specific sequence of DNA?
In situ hybridization (ISH) ## Footnote It identifies cells containing specific mRNAs and determines gene localization.
66
What must happen to DNA and RNA before hybridization in ISH?
They must be denatured to become single-stranded ## Footnote This can be achieved through heat or other agents.
67
What is the main staining method used in histology?
Hematoxylin and eosin (H&E) ## Footnote Hematoxylin acts as a basic stain, while eosin acts as an acidic stain.
68
What are the characteristics of basophilic substances?
They have a net negative charge and react strongly with basic stains ## Footnote Examples include DNA and RNA.
69
What type of microscopy uses UV light to visualize fluorescent molecules?
Fluorescence microscopy ## Footnote It allows localization of fluorescent probes.
70
What is the difference between transmission electron microscopy (TEM) and scanning electron microscopy (SEM)?
TEM produces black & white images with better resolution; SEM produces 3D images of surfaces ## Footnote TEM uses ultrathin sections, while SEM uses coated surfaces.
71
What does autoradiography detect in tissue sections?
Cell components synthesized from radioactive precursors ## Footnote It uses silver grains produced by radiation in photographic emulsions.
72
What is the purpose of enzyme histochemistry?
To visualize specific enzymatic activities in tissue sections ## Footnote This is often done using frozen tissue to preserve enzyme activity.
73
What is the difference between direct and indirect immunohistochemistry?
Direct uses labeled primary antibodies; indirect uses unlabeled primary antibodies with labeled secondary antibodies ## Footnote Indirect is more commonly used for signal amplification.
74
What is a common artifact encountered in tissue sections?
Minor shrinkage of cells or tissue regions ## Footnote This can create artificial spaces and distort structures.
75
Why is understanding the two-dimensional appearance of tissue sections important?
To interpret the actual three-dimensional structure of tissues correctly ## Footnote Components may be missing in front of and behind the observed section.

Basic Histology (5 decks)

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