Histological Micro-techniques

Question 1

What is histology

Answer 1

study of anatomical structures at the microscopic levels

Question 2

what does histological techniques deals with

Answer 2

preparation of tissue for microscopic examination

Question 3

what is histological techniques aimed

Answer 3

to preserve micscropsoic anatomy of the tissue

Question 4

what are the steps of preparing histological slide

Answer 4

fixation, dehydration, clearing and infiltration

Question 5

what is fixation

Answer 5

preservation of tissue in its oringial condition using fixative

Question 6

what is fluid is used for fixation

Answer 6

formaldehyde 0% or acetic acid

Question 7

what conditions is needed for fixation

Answer 7

room temperature

Question 8

how long does fixation take

Answer 8

few hours

Question 9

what factors affect a good fixation

Answer 9

1. fresh tissues
2. good penetration of tissues by fixates (thickness < 1cm )
3. choosing appropriate fixative

Question 10

what does fixation help to do

Answer 10

prevent the autolysis and degradation of the tissue

Question 11

what is dehydration

Answer 11

removal of water from tissues –> water to alcohol

Question 12

how are tissues are dehydrated

Answer 12

by increasing strength of alcohol (70,90 + 100%)

Question 13

what does duration of dehydration depend on

Answer 13

size of tissue
fixative used
type of tissue

Question 14

what is clearing

Answer 14

infilation of paraffin solvent and the tissue will become transparent

Question 15

what clearing agents

Answer 15

xylene, chloroform, benzene

Question 16

what is the aim of clearing

Answer 16

replacing alcohol with a substance in which paraffin wax is solble

Question 17

clearing time depends on what

Answer 17

0.5 - 24 hours according to the size of the sample

Question 18

what is impregnation with wax

Answer 18

allowed to occur at melting point temperature paraffin wave (52-60)

Question 19

what does duration of impregnation with wax depend on

Answer 19

depends on size and types of tissues and the clearing agent employed

Question 20

what is the most common impregnation

Answer 20

paraffin wax

Question 21

what are impregnated tissues are placed on what

Answer 21

mould with their labels and then fresh melted wax is poured in it and allowed to settle and solidify

Question 22

what is embedding

Answer 22

want to embed the tissue we have just processed into a VEX block

Question 23

when wax soldidied what does it look like

Answer 23

the wax is taken out of the tissue block and you will see the tissue centre surrounded by wax in the form of a cue

Question 24

what has to be done after embedding

Answer 24

cutting

Question 25

what is sectioning

Answer 25

to thinly slice the tissue into 4/5 micro thin slices

Question 26

what is microtomy

Answer 26

preparing thin slcies 4 - 6 um thick tissue sections

Question 27

what is the mounting

Answer 27

tissues sections float on warm water and picked up by glass slide

Question 28

what is staining

Answer 28

it is a process by which a tissue section is coloured (to obtain contrast between the parts of the tissue)

Question 29

what are the types of staining

Answer 29

acidic , basic and neutral stains

Question 30

what is acidic stains examples

Answer 30

red or pink ~ eosin

Question 31

what is acidc stainas

Answer 31

tissues components which take this type of stain - acidophilic

Question 32

what is basic stains

Answer 32

tissues components which take this of stains --> basophilic

Question 33

what is the examples of basic stains

Answer 33

blue or purple ~ hematoxylin toluidine blue

Question 34

what is neutral stains

Answer 34

gives different colour components

Question 35

What colours is H + E

Answer 35

Nuclulear appears blue (basophilic) cytoplasm may be pink or red (acidphillic) or blue (basophilloc)

Question 36

what is PAS

Answer 36

Periodic acid schiff reagant this mainly stains glycoproteins

Question 37

what is silver salts

Answer 37

stains fibres black as they are hard to see because they are so thin

Question 38

what is masson's trichome

Answer 38

small muscles are coloured dark maroon and fibres are blue

Question 39

what is artifacts

Answer 39

all of the steps involved in tissue preparation are capable of causing distortions and changes to tissue

Question 40

what are some artifacts

Answer 40

Overstaining or understanding dust/ scratches tissue folds air bubbles nicks in the tissue

Question 41

how can interpreting sections be difficult

Answer 41

oblique 2d structure to show 3d structures