Fixation with formol gel*versus fixation with formalin
Fixation with em Formol gel*
versus
fixation with formalin
Study made at Centro Hospitalar de Setúbal, E.P.E- Portugal, by:
Almas, S., Carretas, S., Fernandes, A., Silva, A. Silva, M.- Técnicas de Diagnóstico e terapêutica do Serviço de
Anatomia Patológica do Centro Hospitalar de Setúbal, E.P.E. e Quintana, C. e Gonçalves M.- Anatomopatologistas
do Serviço de Anatomia Patológica do Centro Hospitalar de Setúbal, E.P.E.
* ANAPAT Formol gel, given by:
Esteriplás - Produtos para a Saúde Lda. -Santa Maria da Feira
Esteriplás- Dep. Técnico
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Fixation with formol gel*versus fixation with formalin
Introdution
Fixation is the most important step during histological processing. Its purpose is to prevent autolysis and
bacterial destruction of the tissues, maintaining its shape and volume during subsequent steps and keep the
tissue closely as possible to its state in vivo.
The fixative most used in routine of pathologic anatomy is 10% buffered formaldehyde as it is compatible
with most complementary techniques that are used routinely in Pathology.
Formaldehyde causes little shrinkage and distortion of tissue, has high penetration speed, since diffuses
rapidly within the tissues, however it possesses a low fixing speed, slow to denature and precipitate proteins
tissue, this being the form of stabilization the chemical components of tissues.
Formaldehyde in liquid form has the disadvantage of producing almost immediately, vapors irritating to the
conjunctiva, upper respiratory tract and skin.
However the same fixative product is available at gel form, whose advantage is the reduction in the
formation of irritating vapors, allowing the operator to be exposed during longer periods without feeling the
effects mentioned above. Because of its consistency, prevents accidental splashing and spillage during
transport and handling of biological samples.
Objetives:
The objective of this study is to compare the morphology, quality and preservation of the biological samples
fixed in 10% buffered formaldehyde in liquid and gel form proceeding to macroscopic and microscopic
evaluations:
- The macroscopic evaluation, compare the visible effects in tissues exposed to formaldehyde buffered 10%
liquid and gel.
- In microscopy evaluation, through the use of routine staining and complementary diagnostic techniques
(histochemistry and immunocytochemistry), comparing the morphology, consistent quality and preservation
of the tissues subject to two kinds of fasteners.
Methodology:
-Samples: Uterus, Kidney, Colon and Gall, welcomed in fresh and sectioned into equal parts for both
fasteners.
-Fixation: Liquid formaldehyde and formaldehyde gel *
- Fixation time:
8h, 24h, 48h, 72h
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Fixation with formol gel*versus fixation with formalin
Evaluation Criteria:
Macroscopy: Method observational
Microscopy:
- H & E staining for morphological and preservation.
- Imunocitoquimica-AE1/AE3 (Colon), Vim (kidney), alpha-actin (uterus), CD34 (gall) to
evaluate the feasibility of etípodos.
- Histochemistry Masson, to assess the viability of the tissue components.
Results:
Tissue type
Fixation time
Fixator kind
Macroscopie
Morfology
H&E
Preservation
Immunocytochemistry
Histochemistry
QUALItY
uterus
kidney
gall
COLÓN
24H
48H
72H
24H
48H
72H
8H
24H
48H
24H
48H
72H
L G
L
G
L
G
L
G
L
G
L
G
L
G
L
G
L
G
L
G
L
G
L
G
2 2
4
4
4
4
2
2
4
4
4
4
2
2
4
4
4
4
2
2
4
4
4
4
4 4
4
4
3
3
4
4
4
4
4
4
2
2
3
3
4
4
4
4
4
4
4
4
4 4
4
4
4
4
4
4
4
4
4
4
2
2
3
3
4
4
4
4
4
4
4
4
3 3
4
3
4
2
2
2
3
3
4
4
2
2
3
3
4
4
3
3
3
3
3
3
3 4
3
3
3
4
4
4
4
4
3
4
4
4
4
4
4
4
3
3
3
3
4
4
16 17 19 18 18 17 16 16 19 19 19 20 12 12 17 17 20 20 16 16 18 18 19 19
Legend:
L = liquid
G = Gel
Classification:
0=Absence; 1= weak ; 2=Moderate ; 3= Strong ; 4= Very strong
Quality: It results from the sum of the evaluation criteria
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Fixation with formol gel*versus fixation with formalin
Conclusion:
During handling of the samples, it was found that by placing the sample container in the gel, it is immediately
immersed in contrast to what happens sometimes in formalin liquid, where samples float.
There was also a decrease of accidental splashing as well as the decrease in strong odors released by
formaldehyde liquid.
Regarding the evaluation criteria, it was found that the results are superimposable on either macroscopically
or in morphology and tissue preservation; slight variations occurred but they were not significant and did not
hamper the use of complementary techniques.
Regarding the different time of fixation the differences aren’t significant exception for 8h clamping used in
gall, whose results were worse. We decided not to use fixture time for the remaining samples of the study.
Despite the small sample size of this study, we found that the formaldehyde gel is feasible for routine
laboratory in Pathology, which is consistent with the study conducted by Michael LaFrinieri.
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