CHAPTER 4: CONVENTIONAL TISSUE PROCESSING (GREGORIOS)

fixation

dehydration

clearing

impregnation

embedding

trimming

section-cutting

staining

mounting

labeling

steps in tissue processing

tissue processing

various steps required to take the tissue from fixation to the state where it is completely infiltrated

xylene

most common clearing agent

paraffin

embedding agent

formalin

most popular fixative

fixation

specimen is placed in a liquid fixing agent

dehydration

carried out by immersing specimen in a series of alcohol (ethanol)

clearing

transferred to an intermediate solvent that is fully miscible with both ethanol and paraffin wax

infiltration

cleared tissue in infiltrated with a suitable histological wax

liquid at 60c

cool to 20c to solidify

embedding

after filtration, tissue is oriented and placed in a mold that is filled with molten wax

double embedding

process by which tissues are first embedded then infiltrated a second time

section-cutting

done with a microtome

3-5um

specimen for h&e are cut?

8-12um

tissues for amyloid deposits cut?

2um

kidney biopsies cut?

0.35-5um

light microscopy cut?

diamond knife

1 micron

plastic blocks are sectioned with?

for about?

15 mins

glass slides placed in over for ___ mins to adhere

mounting

a slight traction is exerted on the end of the ribbon

5-10C

temp of warm bath kep at?

1-2mins

ribbon not left in bath for more than?

staining

xylene removes paraffin and absolute alcohol removes the xylene

automatic tissue processor

this machine allows specimen to be infiltrated with a sequence of different solvents finishing molten in paraffin wax

tissue density and thickness

affects infiltration and subsequent sectioning of tissues

agitation

increases flow of fresh fluids in and around the tissues

37-45C

temp that can speed up fluid penetration and tissue processing

2-3C

maintain embedding waxes @