CLEARING AND EMBEDDING

XYLENE

MOST RAPID, MOST COMMONLY USE

MILKY: IF INADEQUATE DEHYDRATION

TOLUENE

SUBSTITUE FOR XYLENE, BENZEN, EXPENSIVE

BENZENE

RAPID ACTING

URGENT BIOPSIES

TOXIC: APLASTIC ANEMIA

CHLOROFORM

LARGE AND TOUGH TISSUES,

TOXIC: HEPATOTOXIC

CARBON TETROXIDE

CHEAPER, HIGHLY TOXIC

CEDARWOOD OIL

CNS, SMOOTH MUSCLE AND SKIN

ANILINE OIL

EMBRYOS OR DELICATE SPECIMENS

CLOVE OIL

EASILY ADULTERED

METHYL BENZOATE / SALYCILATE

DOUBLE EMBEDDING TECHNIQUE

IMPREGNATION

AKA INFLITRATION

25X

IMPREGNATION: VOLUME =

PARAFFIN WAX

CELLOIDIN

GELATIN

PLASTIC

EXAMPLES OF MEDIUM

PARAFFIN WAX

Simplest, Most common, BEST EMBEDDING MEDIUM

56C

Paraffin wax melting point:

2-5C ABOVE MP OF WAX

PARAFFIN OVEN:

6-10C BELOW MP OF WAX

PARAFFIN FLOTATION BATH:

EMBEDDING

Impregnated tissue is placed into a precisely arranged position in a mold containing a medium

NATURE AND SIZE OF TISSUE

TYPE OF CLEARING AGENT

FACTORS AFFECTING IMPREGNATION

MANUAL

4 CHANGES OF WAX AT 15 MINS INTERVAL

AUTOTECHNICON

EXAMPLE OF AUTOMATED IMPREGNATION

VACUUM EMBEDDING

Impregnation under negative atmospheric pressure

PARAPLAST

PARAFFIN SUBSTITUES: MP 56-57C, Elastic, Resilient,

Paraffin + synthetic plastic polymers

EMBEDDOL

PARAFFIN SUBSTITUES: MP 56-58C, Less brittle, Less compressible

ESTER WAX

PARAFFIN SUBSTITUES: MP: 46-48C

WATER SOLUBLE WAX

PARAFFIN SUBSTITUES: MP: 38-42 C AT 45-56C, NO Dehydration and clearing.

EX: CARBOWAX AND PEG

TISSUE MAT

PARAFFIN SUBSTITUES: CONTAINS RUBBER

CELLOIDIN

PARAFFIN SUBSTITUES: Purified nitrocellulose

CELLOIDIN IMPREGNATION

Specimen: Large hollow cavity which tends to collapse, dense and hard tissue (bones) and large tissue (embryo)

WET CELLOIDIN

Bones, teeth, large section of whole organs

After embedding → Stored in 70-80% ALCOHOL

DRY CELLOIDIN

Whole eye sections

After embedding → Stored in Gilson’s Mixture

NITROCELLULOSE

Celoidin soluble in equal concentration of alcohol and ether lower viscosity forms harder tissue blocks for better cutting of thinner sections.

GELATIN IMPREGNATION

Rarely use, water solube, uses 1% Phenol to prevent molds

EMBEDDING

AKA CASTING OR BLOCKING

5-10 C ABOVE MP

EMBEDDING: PARAFFIN WAX:

TUBULAR TISSUE

All layers in transverse section

SKIN

All layers should come

ENDOMETRIAL CURETTING

Keep in center

LONG TISSUE

Keep diagonally

INTESTINE

All layers should come

MEMBRANE

Swiss role

ORIENTATION

process by which a tissue is arranged in precised position in the mold during embedding

LEUCKHART’S

Two L-shape heavy brass/metal arranged on a flat metal shape

COMPOUND

Series of interlocking plates resting on a flat metal base

PLASTIC

Has a special stainless steel base mold fitted in a plastic embedding ring which later serves as block holder during cutting

DISPOSABLE

PEEL AWAY

PLASTIC ICE TRAYS

PAPER BOAT

GILSON’S MIXTURE

Equal parts of Chloroform and Cedarwood Oil

GELATIN IMPREGNATION

For histochemical and enzyme studies