Tissue and organ fixation for educational and scientific purpose

1. Improved Medical Education in Basic
Sciences
for Better Medical Practicing
ImproveMEd
Tissue and organ fixation for
educational and scientific purpose

2. • Purpose of fixation
• Fixation agents
• Fixation procedure

3. 1. Purpose of fixation
 preservation of organs, tissues and cellular arhitecture in so called - „life-like state“
Fixative agents

4.  preserving human cadavers donated for scientific and educational purpose
m. deltoideus inferior hyoid muscles

5.  to prevent decomposition, putrefaction and autolysis
enzyme
molecule
decomposition (products)
enzyme stays unchanged

6. fixative

7. • The inevitable consequences of „cross-linking” are the hardness of the tissues or
organs that pass through the fixating procedure

8. 2. Fixation agents
 ALDEHYDES
 OXIDIZING AGENTS
 ALCOHOL BASED FIXATIVES
 METALLIC GROUP OF FIXATIVES

9. FIXATION
Physical process Chemical process

10. C
O
H H
FORMALDEHYDE

11. FORMALIN
Formaldehyde 37 – 40 % Water 60 – 63 %

12. Formaldehyde
H2O
Water
Methylene glycol

14. Formaldehyde
in water
Methylene
glycol
Polyoxy
methylene
glycol
Methylene
glycol
(dehydration &
depolymerization)

15. OH

16. CO2+H2O
Methanol Formaldehyde Formic acid
Alcohol
dehydrogenase
Formaldehyde
dehydrogenase

17. If there was an ideal fixative, it should have certain properties:
 Not to harden tissue, organs and cadavers
 To allow fine coloring of tissue for further analysis
 Not be toxic to humans and animals
 Acceptable price
 To date, no ideal fixative has been found

18. 3. Fixation procedure
 Using only formaldehyde as a fixative does not yield good results for long term preservation
 Formaldehyde needs to be combined with other agents
 There are specialized protocols for fixation of CADAVERS or just isolated ORGANS

19. KAISERLING’S SOLUTIONS
• Preservation of individual isolated organs for education
• Advantage of this solutions is to preserve the approximate color of the tissue

20. Solutions preparation:
 Kaiserling I: 85g potassium acetate, 45g potassium nitrate, 4800mL formalin solution (3 - 4%)
 Kaiserling II: ethyl alcohol, 80 – 95%
 Kaiserling III: 200g potassium acetate, 300mL glycerin, 900mL tap water

22. PRETORIUS PROTOCOL
 Standardized method for cadaver fixation for educational purposes
 Advantage of this protocol is the durability of cadaver and low price of fixation
 Disadvantage – brown coloring of the tissue

23.  Solution preparation:
• 96 % ethanol
• Formalin (3 – 4 %) 500 mL
• Tap water 750 mL
• 80 % liquid phenol 3,5 L
Procedure of fixative injection:
• injection of about 5 L of formalin at a pressure of 1 to
1,5 kPa in the cadaver (through the femoral artery)

24. cadaver 60 kg → 25 L of fixative → fixation time is about 3 to 5 years

26.  Cadaver maintenance
• Cover with a moistened fabric with humectant and keep it in a cool room
 Humectant preparation:
• Glycerine – 250 mL
• 80 % liquid phenol – 250 mL
• Tap water – 1 L

27. THANK YOU FOR YOUR
ATTENTION!