Tissue prep and staining Flashcards Preview

histology (E1 Woods) > Tissue prep and staining > Flashcards

Flashcards in Tissue prep and staining Deck (28):
1

what are the steps needed to prepare tissues for observation

fixing, dehydration, removal of alcohol, embedding

2

what does fixation prevent

further deterioration of the specimen and helps to harden the tissue prior to embedding and sectioning

3

what is the main downfall of fixation

it radically distorts the specimen

4

what is one of the most widely used fixing agents

Formalin

5

what does formalin do

fixing agent that reacts with the amino acids of the tissue proteins and stabilizes tissue structure to prevent further deterioration

6

what do acid fixatives fix? don't fix?

fix: chromatin, nuclei and spindle fibers
don't fix: mitochondria and nucleoplasm

7

name three acid fixatives

carnoy's fluid
zenker's fluid
Bouin's fluid

8

what is Carnoy's fluid good for

good general fixative and is useful for preserving glycogen in animal tissues

9

what is Zenker's fluid good for

useful when sharp histological detail is desired, but must be washed out carefully to prevent the precipitation of black crystals

10

what is Bouin's fluid good for

widely used general fixative that gives cytological detail

11

when are basic fixatives usually used

when mitochondrial staining is desired

12

what is the main downfall of basic fixatives

chromatin is dissolved

13

what are 2 main fixatives for TEM

Glutaraldehyde: preserves proteins by cross-linking them
Osmium tetroxide: reacts with lipids and imparts electron density to cell and tissue structure

14

why must dehydration occur for tissue fixing and embedding?

because the tissue sample will eventually be embedded and infiltrated with a hydrophobic material (usually paraffin)

15

what is clearing?

consists of replacing the alcohol with an agent such as xylene or cedar oil

16

what are the steps of embedding

1. the tissue specimen is moved sequentially through several melted paraffin baths
2. after the final bath the specimen is placed in a mold that is then filled with melted paraffin
3. the paraffin mold is rapidly hardened by placing it in a cold water bath

17

steps to prepare for staining

1. paraffin must be removed from the section, which is now mounted on a microscope slide (accomplished with xylene)
2. xylene must be removed using a graded series of alcohol down to water
3. stains are then applied and the section is again dehydrated through a graded series of alcohols
4. the alcohol is removed with xylene
5. a drop of cement followed by a cover slip is applied

18

what is hematoxylin derived from

logwood as hematein

19

what can orcein and resorcin fuchsin stains be used for?

to reveal elastic material

20

what is silver impregnation useful for

to show reticular fibers and basement membranes

21

how do acid dyes bind to tissue components?

by forming electrostatic linkages with cationic groups such as the amino groups of proteins

22

define metachromasia

phenomenon whereby a dye changes color after reacting with a tissue component

23

what can histochemical techniques be used for

to study the chemistry of cells and tissues

24

what does the schiff reaction depend on

formation of aldehyde groups following exposure to HCL or periodic acid

25

what is periodic acid used for

used to cleave bonds between adjacent carbons of carbohydrates and form aldehyde groups

26

what is best carmine used for

dye that may be used to demonstrate glycogen deposits

27

what can immunocytochemical techniques be used for

to study the presence of specific tissue constituents (antigens) by using monoclonal antibodies

28

what are monoclonal antibodies derived from

activated B cell clones exposed to a specific antigen