HISTOPATHOLOGY
TISSUE PROCESSING
π¦ Medical Lab Academy
π’ @MedicallabAcademy
π¬ WHAT IS TISSUE PROCESSING?
π§ Definition:
Tissue processing is the method of removing water from fixed tissue and replacing it with paraffin wax so the tissue becomes firm and can be cut into thin microscopic sections.
π― OBJECTIVES OF PROCESSING
π’ Remove water from tissue
π‘ Replace water with embedding medium
π΅ Make tissue firm for sectioning
π£ Preserve tissue morphology
π΄ Prepare tissue for uniform staining
β Exam clue:
No processing β No section β No diagnosis
βοΈ MAIN STEPS OF TISSUE PROCESSING
π‘ 1. DEHYDRATION
π‘ Removes water from tissue
𧴠Reagents:
70% alcohol β 80% β 95% β Absolute alcohol
π§ Principle:
Gradual replacement prevents tissue distortion.
β οΈ Too rapid dehydration β Tissue shrinkage
π΅ 2. CLEARING
π‘ Removes alcohol & prepares tissue for wax
𧴠Agents:
β Xylene β (Most common)
β Toluene
β Benzene
β Chloroform
ποΈ Tissue becomes transparent
π Exam favorite:
Clearing agent = Xylene
π΄ 3. INFILTRATION
π‘ Wax enters tissue spaces
π₯ Medium: Paraffin wax
π‘ Temperature: 56β60Β°C
π§ Wax replaces clearing agent and gives strength.
β οΈ Overheated wax β Tissue becomes hard
π€ 4. EMBEDDING
π‘ Tissue is placed in mold and wax solidifies.
π― Importance:
Correct orientation ensures correct diagnosis.
π Example:
Epithelium must be cut perpendicular to surface.
π Final product = Paraffin block
𧱠EMBEDDING MEDIA
π‘ Paraffin wax β Most used
π΅ Water-soluble wax β Special cases
π£ Plastic resin β Electron microscopy
β MCQ tip:
Most common = Paraffin wax
β οΈ FACTORS AFFECTING QUALITY
π Tissue thickness (ideal 3β5 mm)
π§ͺ Proper fixation first
β± Correct timing
𧴠Reagent purity
π₯ Correct wax temperature
β Golden rule:
Bad fixation β Bad processing
β ARTEFACTS FROM POOR PROCESSING
π» Tissue shrinkage
π» Poor infiltration
π» Tissue too hard
π» Distorted orientation
π These lead to wrong diagnosis
π π±πππ ππππ
@MedicallabAcademy
@MedicallabAcademy
@MedicallabAcademy
β€οΈ Like β’ π Share β’ π Support
βββββββββββββββββββββββββ
TISSUE PROCESSING
π¦ Medical Lab Academy
π’ @MedicallabAcademy
π¬ WHAT IS TISSUE PROCESSING?
π§ Definition:
Tissue processing is the method of removing water from fixed tissue and replacing it with paraffin wax so the tissue becomes firm and can be cut into thin microscopic sections.
π― OBJECTIVES OF PROCESSING
π’ Remove water from tissue
π‘ Replace water with embedding medium
π΅ Make tissue firm for sectioning
π£ Preserve tissue morphology
π΄ Prepare tissue for uniform staining
β Exam clue:
No processing β No section β No diagnosis
βοΈ MAIN STEPS OF TISSUE PROCESSING
π‘ 1. DEHYDRATION
π‘ Removes water from tissue
𧴠Reagents:
70% alcohol β 80% β 95% β Absolute alcohol
π§ Principle:
Gradual replacement prevents tissue distortion.
β οΈ Too rapid dehydration β Tissue shrinkage
π΅ 2. CLEARING
π‘ Removes alcohol & prepares tissue for wax
𧴠Agents:
β Xylene β (Most common)
β Toluene
β Benzene
β Chloroform
ποΈ Tissue becomes transparent
π Exam favorite:
Clearing agent = Xylene
π΄ 3. INFILTRATION
π‘ Wax enters tissue spaces
π₯ Medium: Paraffin wax
π‘ Temperature: 56β60Β°C
π§ Wax replaces clearing agent and gives strength.
β οΈ Overheated wax β Tissue becomes hard
π€ 4. EMBEDDING
π‘ Tissue is placed in mold and wax solidifies.
π― Importance:
Correct orientation ensures correct diagnosis.
π Example:
Epithelium must be cut perpendicular to surface.
π Final product = Paraffin block
𧱠EMBEDDING MEDIA
π‘ Paraffin wax β Most used
π΅ Water-soluble wax β Special cases
π£ Plastic resin β Electron microscopy
β MCQ tip:
Most common = Paraffin wax
β οΈ FACTORS AFFECTING QUALITY
π Tissue thickness (ideal 3β5 mm)
π§ͺ Proper fixation first
β± Correct timing
𧴠Reagent purity
π₯ Correct wax temperature
β Golden rule:
Bad fixation β Bad processing
β ARTEFACTS FROM POOR PROCESSING
π» Tissue shrinkage
π» Poor infiltration
π» Tissue too hard
π» Distorted orientation
π These lead to wrong diagnosis
π π±πππ ππππ
@MedicallabAcademy
@MedicallabAcademy
@MedicallabAcademy
β€οΈ Like β’ π Share β’ π Support
βββββββββββββββββββββββββ