Intro to Histo

Question 1

histology

Answer 1

study of cells and body tissues

Question 2

purpose of histo

Answer 2

. understand tissue structure at levels not visible to eye
. understand relationship between structure/function
. establish basis for histopathology

Question 3

types of microscopy

Answer 3

light microscopy (LM) & electron microscopy (EM)

Question 4

LM

Answer 4

based on interactions of light and tissue with optical lens to focus beam of photons on speciman

Question 5

EM

Answer 5

. based on interactions of electrons and tissue
. resolving power 1000x LM
. magnification 100xLM

Question 6

types of EM

Answer 6

transmission EM (TEM) and scanning EM (pseudo 3D views)

Question 7

micrometer

Answer 7

(um), 0.001 mm or 10^-6m

Question 8

nanometer

Answer 8

(nm), 0.001 um or 10^-9m

Question 9

resolution

Answer 9

smallest distance at which 2 points can be distinguished from each other

Question 10

unaided eye resolution

Answer 10

0.2 mm

Question 11

LM resolution

Answer 11

0.2 um (x1000-1500 magnification)

Question 12

TEM resolution

Answer 12

3 nm (x120,000 magnification)

Question 13

preparation of tissue for LM steps

Answer 13

fixation, dehydration/clearing/embedding, sectioning, and staining

Question 14

types of fixation of tissues

Answer 14

chemical w/ formalin, physical by freezing

Question 15

purpose of fixation of tissues

Answer 15

preserve microscopic organization of cells, tissues, organs

Question 16

dehydration, clearing, and embedding steps for formalin-fixed tissues

Answer 16

.H2O replaced by organic solvent (ethanol)
. ethanol replaced by clearing agent (xylene)
. xylene replaced by paraffin

Question 17

sectioning of tissue

Answer 17

steel blade of microtome used to cut 1-10 um thick sections

Question 18

what are frozen tissues sectioned with?

Answer 18

cryostat (freezing microtome)

Question 19

staining of tissues

Answer 19

most dyes act as acids/bases & form ionic bonds

Question 20

most common stain

Answer 20

Hematoxylin and eosin

Question 21

Is hematoxylin acid or basophilic

Answer 21

basophilic (neg. charged ions that bond to pos. charged tissues)

Question 22

what color does hematoxylin stain?

Answer 22

blue

Question 23

Is eosin acid or basophilic

Answer 23

acidophilic (pos. charged ions that bond to neg. charged tissues)

Question 24

what color does eosin stain?

Answer 24

pink

Question 25

what is orcein stain used for?

Answer 25

visualize elastin/elastic fibers

Question 26

what is sudan black stain used for?

Answer 26

visualize lipids

Question 27

what is silver salts used for as stain?

Answer 27

see reticular fibers

Question 28

what is periodic acid-Schiff (PAS) stain used for?

Answer 28

see carbs/mucus

Question 29

what is Wright-Giemsa stain used for?

Answer 29

differential blood cell staining for peripheral blood smears or bone marrow aspirates

Question 30

what is immunocytochemistry stain based on?

Answer 30

specific binding of antibody to cell/tissue

Question 31

Steps to prep tissue for EM

Answer 31

. fixation w/ glutaraldehyde
. stain w/ heavy metal
. freeze fracture and freeze etch (don’t require fixation)

Question 32

why is not fixing and embedding important for EM tissues?

Answer 32

important too see cell membrane properly

Question 33

artifacts

Answer 33

structural abnormalities from tissue prep

Question 34

types of artifacts

Answer 34

. tissue shrinkage
. loss of lipids
. 3D structures sectioned on 2D planes

Question 35

how many basic tissues make up every organ?

Answer 35

4

Question 36

microanatomy

Answer 36

cytology + histology

Question 37

T/F the ability to magnify is more limiting than the ability to resolve

Answer 37

F

Question 38

electron dense color in EM

Answer 38

dark color

Question 39

electron lucent color in EM

Answer 39

white/light color

Question 40

how big is rbc

Answer 40

7-8 um