Introduction

Many persons working in anatomy and embalming are exposed to formaldehyde, which is a relatively toxic material. ( 1 ) Formaldehyde is a highly reactive, colorless, smelly gas that dissolves in water and can irritate the skin and eyes. ( 2 ) Formalin has several medicinal applications, including embalming animals, preserving surgical specimens, and preparing specimens for anatomy. ( 3 ) When the body is exposed to foreign substances such as microorganisms and toxic substances, it triggers inflammation, to varying degrees. ( 4 ), Elimination of pathogenic stimuli and restoration of affected tissues are made possible through this immune response. ( 5 ) The skin is the first line of defense against pathogens and dangerous chemicals, if these agents cross the skin, innate immunity begins, which causes acute inflammation. ( 6 ) Typical signs of inflammation include redness, high temperature, swelling, and discomfort. ( 7 ) Due to the increasing advances in the field of medicine, the current understanding of inflammation has expanded greatly over the years and there are still some hidden issues. ( 8 ) Previous research has shown that exposing the body to external contaminants causes inflammation in both significant and secondary organs. ( 9-10-11 ) This was discovered in a study that looked at changes in tissue that occur after feeding mice with a type of toxin called Dioctyl sodium sulfosuccinate (DSS)

Poison ( 12 ), If amyloid infiltration and dead cells are detected in all lymphocytes in mouse spleen ( 13 ), however, a study confirmed that exposure to toxic substances such as formalin and other chemicals causes tissue pathological changes. This is observed in internal organs (liver, kidney, heart muscle, lung, stomach, and nerve tissue) of experimental mice, including congestion, degeneration, fibrosis, negation, necrosis, and discharge. ( 14 ) A large body of research has revealed that injecting animals with formalin enhances pain by stimulating neurons in the central nervous system. ( 15 ) On the other hand, inflammatory sites emit mediators that promote inflammation, including cytokines and chemokine's, they cause pain behavior by enhancing the sensitivity of peripheral neurons that detect pain, it causes inflammatory proteins, including cytokines (TNF-Alpha, IL-1) and other inflammatory agents, to be produced. ( 16 ) At the same time, they cause an increase in intracellular oxidation, which in turn causes alterations in superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) own unique set of triggers and control mechanisms, it is thought that inflammation, because of its vast and ubiquitous nature. ( 17 ) Exposure to high concentrations of formaldehyde during pregnancy is more likely to affect embryonic development and create heart defects. ( 18 ) The main objective of this study was to determine the changes that occur in spleen tissue due to exposure to formalin at different time periods.

Materials and Methods

Laboratory animal husbandry and laboratory

Laboratory animals (male) brought male Rars from the Iraqi Center for Research on Cancer and Medical genetics The animals were bred at the Animal House of the Faculty of Education for Pure Sciences - Basra University, under an appropriate temperature of 25-20 degrees Celsius. They included 12 hours and 12 hours of darkness. fed on a leech of 30% flour, 20% milk, 30% bran, and 30 water, for the purpose of proliferating it and getting enough of it to complete the experiment, after which female Rats from the multiplication process were isolated) with close ages (four months) and recorded weights (190 – 220 g) of laboratory animals.

Subcutaneous injection method

Rodents were placed into three groups, each with five individuals. Five of them were from the negative control group (A), which received normal saline injections. Both groups (B and C) were injected with formalin at a concentration of 2% by 20 micrometers. If the injection period of group B is a week, group C lasts for two weeks, with the duration of the injection being 72 hours for both groups. (B) was dissected one week following the final injection of formalin. The second group (C) was dissected two weeks following the final injection of formalin. To assess the chemical's impact, the organs were extracted and compared to the negative control group. ( 19 )

Investigation of Histopathological changes in tissue alterations in rat spleen

In this research study, the method Humason was adopted in preparing passages to study the pathological effects of formalin.( 20 ) Animals were dissected, and organs were fixed in a beaker containing 10% formalin for 48 hours. Samples were dried in ethanol solutions, submerged in xylene, and immersed in paraffin wax. Tissue slices were flattened with paraffin strips and cut to 7 μm thickness. The seats were dried, wax removed, and run through ethyl alcohol for 5 minutes each. Canada balsam was used, and the cover was slipped, examined with a Leica imaging microscope, and photographed. The results provide valuable insights into animal anatomy.( 21 )

Results

The results of the tissue section of the spleen showed that the effect of formalin in group (B) was greater than in group (C) compared with group( A), the negative control. This was demonstrated through histological changes, which showed atrophy of the white and red pulp of the spleen. The atrophy of the white lymphocytes includes the loss of lymphocytes in T cells (lymphoma surrounding arteries) and B cells (experiments, microbial centers, and marginal zones), figures (1,2 , and 6 ) illustrate this. There is an abnormal and abundant proliferation of macrophages throughout the red and white pulp of the spleen, as seen in Figure 4. compared to Figure 3 .

Figure (1).

Figure (2).

Figure (3).

Figure (4).

Figure (5).

Figure 6.

Discussion

During the current study, after exposing two groups of rats to the injection of a chemical substance directly under the skin, this induced inflammation within the body due to the entry of the foreign substance, which in turn led to the activation of biological stimuli such as the response signals released by the damaged tissue that led to its exposure to the chemical (Formalin) to cause damage or dysfunction. ( 22 ), a guest of the same area and surrounding tissue, which is consistent with the study. ( 23 )

This research has shown that the exposure of the body to formalin through subcutaneous injections leads to some changes in the appearance of spleen tissue if textile images show some cellular decomposition that has led to the emergence of small empty spaces (figures 2,4 , and6 ), which attributed to the presence of necrosis in spleen cells that was the result of high oxidative voltage in the body and, in particular, the blood vessel mentioned. (24) in his study. Still, these changes were consistent with the research study on the precise description of necrosis ( 25 ).

The appearance of apoptosis in lymphocytes, which usually occurs naturally in germ centers in rodent spleen. However, it can increase when the animal is exposed to serious chemical or external injury. Here, an unprecedented or faster stimulation of programmed cellular death in lymphocytes is observed in the white core part and is on its way to cellular death. It can be traced back to the existence of a dysfunction of free radicals in tissue. Oral exposure to formaldehyde has also been shown to cause DNA damage, apoptosis, and device injury. This is consistent with the study. ( 26 )

The cause of the first group (B) spleen can also be returned more than the other group (C). As formalin is a toxic substance in high concentrations that triggers the release of response signals, the more the response is evidence of increased signals within the body, which in turn leads to damage to tissue and cells, and this happened with spleen tissue at the beginning of exposure to the chemical in the first week, This was consistent with the study, which explained the overproduction of inflammatory cytokines as a result of formalin exposure to tissue damage, changes in circulation, organ failure and eventual death.( 27 )

Conclusion

This research shows that chemical exposure induces alterations at the cellular level inside the body's organs. Formalin is an inflammatory agent that affects the spleen, which is intricately linked to both the lymphatic and circulatory systems.

Conflicts of interest

The authors declare that there is no conflict of interest.

Ethical Clearance

This work is approved by The Research Ethical Committee.

References

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