DEHYDRATION
MANDATORY STEP in tissue processing & may be carried out using autotechnicon unlike in decalcification.
Removal of intercellular & extracellular water from tissues after fixation & prior to wax impregnation
Uses dehydrating agents such as ascending grades/concentration of alcohol (commonly used)
Amount of dehydrating agent (volume): not less than 10x the volume of the spx
Required initial concentration:
For ROUTINE:
- between 70-80% (sa unang lalagyan, di pweding 90% muna kase it will harden only the surface, the
deeper parts of the tissue will not be completely penetrated; Also, very low concentration as initial
because it will macerate tissues)
- You can use 30% as initial concentration only when processing delicate tissues like embryo.
8 DEHYDRATING AGENTS
1. ACETONE
▪ Double purpose:
a. Fixation
b. Dehydration
▪ Not commonly used because it evaporates easily and it is highly flammable
▪ Fast-acting so they are suited ONLY for urgent biopsies, however, it is NOT for routine dehydration
2. ETHYLENE GLYCOL MONOETHYL ETHER
▪ aka Cellosolve
▪ Characteristics:
1. Combustible at 110-120 degF
2. Toxic by ingestion, inhalation, and by skin contact (prolong exposure)
3. Toxic to reproductive, fetal, urinary, and blood systems
4. Decomposes upon exposure to sunlight
3. TRIETHYL PHOSPHATE
▪ Not commonly used
▪ Causes only minimum shrinkage
▪ Recommended for dehydrating section and smears
4. TETRAHYDROFURAN (THF)
▪ Double purpose:
a. Dehydrating agent
b. Clearing agent
▪ Toxic if ingested or inhaled
▪ Vapors causes nausea, dizziness and headache
▪ With offensive odor, so the room should be well ventilated
▪ May cause conjunctival irritation
MANDATORY STEP in tissue processing & may be carried out using autotechnicon unlike in decalcification.
Removal of intercellular & extracellular water from tissues after fixation & prior to wax impregnation
Uses dehydrating agents such as ascending grades/concentration of alcohol (commonly used)
Amount of dehydrating agent (volume): not less than 10x the volume of the spx
Required initial concentration:
For ROUTINE:
- between 70-80% (sa unang lalagyan, di pweding 90% muna kase it will harden only the surface, the
deeper parts of the tissue will not be completely penetrated; Also, very low concentration as initial
because it will macerate tissues)
- You can use 30% as initial concentration only when processing delicate tissues like embryo.
8 DEHYDRATING AGENTS
1. ACETONE
▪ Double purpose:
a. Fixation
b. Dehydration
▪ Not commonly used because it evaporates easily and it is highly flammable
▪ Fast-acting so they are suited ONLY for urgent biopsies, however, it is NOT for routine dehydration
2. ETHYLENE GLYCOL MONOETHYL ETHER
▪ aka Cellosolve
▪ Characteristics:
1. Combustible at 110-120 degF
2. Toxic by ingestion, inhalation, and by skin contact (prolong exposure)
3. Toxic to reproductive, fetal, urinary, and blood systems
4. Decomposes upon exposure to sunlight
3. TRIETHYL PHOSPHATE
▪ Not commonly used
▪ Causes only minimum shrinkage
▪ Recommended for dehydrating section and smears
4. TETRAHYDROFURAN (THF)
▪ Double purpose:
a. Dehydrating agent
b. Clearing agent
▪ Toxic if ingested or inhaled
▪ Vapors causes nausea, dizziness and headache
▪ With offensive odor, so the room should be well ventilated
▪ May cause conjunctival irritation
