Histology Chapter 1: Histological Methods

Front 1

What is histology?

Back 1

The study of tissues

Front 2

study of tissues = ?

Back 2

studying the make-up of organs

Front 3

What makes up organs?

Back 3

Orderly combinations of several tissues

Front 4

What are the two parts of tissues?

Back 4

cells + extracellular matrix

Front 5

Why are microscopes used in histology?

Back 5

Because of the small size of specimens

Front 6

What are the four main types of tissue?

Back 6

1. epithelium
2. connective tissue
3. muscle tissue
4. Nervous tissue

Front 7

What are the main functions of epithelium?

Back 7

Functions:
1. protection
2. secretion
3. absorption

Front 8

Tissues composed of layers of cells that cover organ surfaces (i.e., surface of skin, inner lining of digestive tract)

Back 8

epithelium

Front 9

holds everything together and is characterized by separation of cells by non-living material, ECM

Back 9

Connective tissue

Front 10

Blood and bone are examples of what kind of tissue?

Back 10

connective tissue

Front 11

Contractile tissue of the body

Back 11

muscle tissue

Front 12

What is the main function of muscle tissue?

Back 12

To produce force and cuase motion, either locomotion or movement within internal organs

Front 13

What are the three types of muscle tissue?

Back 13

1. visceral or smooth-organs
2. skeletal-attached to bone, mobility
3. cardiac-heart

Front 14

Cells forming the brain, spinal cord and peripheral nervous system

Back 14

nervous tissue

Front 15

What are qualities of tissue?

Back 15

1. thick
2. NOT translucent
3. Decompose after death
4. lack color/contrast
5. made up of cells

Front 16

What are the steps for staining?

Back 16

1. Extraction
2. Fixation
3. Embedding
4. Sectioning Tissue
5. Staining
6. Viewing

Front 17

Why must most tissues be collected quickly?

Back 17

To avoid degradation

Front 18

Tissues can only be taken from non-living specimens. T/F

Back 18

False, tissues can be taken from both living and non-living specimens

Front 19

After extraction, how is tissue fixed?

Back 19

Either chemically fixed or frozen in a matrix

Front 20

For a frozen section, histology should be fixed in a chemical fixative prior to freezing. T/F

Back 20

False, histology should NOT be fixed in chemical fixative. It should be (1) dried, (2) surrounded by cryoprotectant, and (3) snap frozen (77K)

Front 21

What is the best thickness for a tissue placed in a fixative?

Back 21

0.2-0.5cm, sections that are thicker require time for the fixative to permeate to the center, resulting in possible degradation

Front 22

The volume of the fixative in paraffin embedding should be the same as that of the specimen. T/F

Back 22

False, it should be at least 10X that of the specimen

Front 23

What are the two main reasons for fixation?

Back 23

1. to maintain same structure
2. eliminate tissue digestion by enzymes or bacteria (i.e., pancreas)

Front 24

What cross-linking agent is used to prepare a specimen for histological staining?

Back 24

fixative

Front 25

Fixation can either be physical or chemical. T/F

Back 25

True.

Front 26

What is the best thickness for a tissue placed in a fixative?

Back 26

0.2-0.5cm, sections that are thicker require time for the fixative to permeate to the center, resulting in possible degradation

Front 27

The volume of the fixative in paraffin embedding should be the same as that of the specimen. T/F

Back 27

False, it should be at least 10X that of the specimen

Front 28

What are the two main reasons for fixation?

Back 28

1. to maintain same structure
2. eliminate tissue digestion by enzymes or bacteria (i.e., pancreas)

Front 29

What cross-linking agent is used to prepare a specimen for histological staining?

Back 29

fixative

Front 30

Fixation can either be physical or chemical. T/F

Back 30

True.

Front 31

What is a commonly used fixative?

Back 31

4% formaldehyde; it reacts with amine group of tissue proteins

Front 32

Why is embedding an essential step to histological staining?

Back 32

Because it helps maintain the same rigid consistency to tissue in sectioning

Front 33

What are two common solutions used for embedding?

Back 33

1. paraffin, 2. plastic resins

Front 34

When is it appropriate to use resins for embedding?

Back 34

light microscopy and EM

Front 35

What step proceeds embedding?

Back 35

Dehydration (ethanol series) and clearing (xylene)

Front 36

What instrument is used to section tissues?

Back 36

a cutting instrument called a microtome

Front 37

A microtome cuts sections of what thickness?

Back 37

1-10 um, or 0.001mm-

Front 38

What are the advantages in using a cryostat rather than a microtome?

Back 38

1. It's faster
2. Preserves lipids*

Front 39

What is meant when a tissue is considered acidophilic?

Back 39

it has an affinity for acid dye

Front 40

What is meant when a tissue is considered basophilic?

Back 40

it has an affinity for basic dye

Front 41

Describe H&E staining

Back 41

Hematoxylin (blue): stains nucleus (basic dye)
Eosin (pink): stains cytoplasm/collagen (acidic dye)

Front 42

Pink, acidic dye, stains cytoplasm, collagen/elastic fibers

Back 42

eosin

Front 43

Blue, basic dye, stains nucleus

Back 43

hematoxylin

Front 44

What does trichrome staining do?

Back 44

differentiate collagen and smooth muscle

Front 45

mixture of methylene blue and eosin; stains chromosomes-attracted to phosphate group of DNA

Back 45

giemsa

Front 46

type of dye that forms a salt linkage with a + charged tissue group

Back 46

acid dye

Front 47

type of dye that has a + charge

Back 47

basic dye

Front 48

Type of dye that stains glycogen and various carb. containing molecules

Back 48

periodic acid Schiff stains (PAS)

Front 49

purple stain in area of polysaccharide

Back 49

Schiff's reagent, ex: glycogen in liver, striated muscle

Front 50

What stain is used to identify reticular fibers?

Back 50

silver stain

Front 51

The branch of science that deals with the chemical composition of cells and tissues of the body

Back 51

histochemistry

Front 52

the identification and localization of the different chemical compounds and their activities within the cell

Back 52

cytochemistry

Front 53

the application of immunochemical techniques to cytochemistry; includes direct and indirect fluorescent antibody techniques

Back 53

immunocytochemistry

Front 54

What histoenzymatic method is used to demonstrate lysosomes?

Back 54

acid phosphatases

Front 55

What histoenzymatic method splits bond between phosphate and alcohol residue in phosphorylated molecules?

Back 55

phosphatases

Front 56

What histoenzymatic method transfers H from one substrate to another?

Back 56

dehydrogenases

Front 57

What histoenzymatic method transfers H ions to H2O2 forming H2O and is important for diagnosing leukemia?

Back 57

Peroxidase