Improved Preservation of Mouse Intestinal Tissue Using a Formalin/Acetic Acid Fixative and Quantitative Histological Analysis Using QuPath.

The architecture and morphology of the intestinal tissue from mice or other small animals are difficult to preserve for histological and molecular analysis due to the fragile nature of this tissue. The intestinal mucosa consists of villi and crypts lined with epithelial cells. In between the epithelial folds extends the lamina propria, a loose connective tissue that contains blood and lymph vessels, fibroblasts, and immune cells. Underneath the mucosa are two layers of contractile smooth muscle and nerves. The tissue experiences significant changes during fixation, which can impair the reliability of histologic analysis. Poor-quality histologic sections are not suitable for quantitative image-based tissue analysis. This article offers a new fixative composed of neutral buffered formalin (NBF) and acetic acid, called FA. This fixative significantly improved the histology of mouse intestinal tissue compared to traditional NBF and enabled precise, reproducible histologic molecular analyses using QuPath software. Algorithmic training of QuPath allows for automated segmentation of intestinal compartments, which can be further interrogated for cellular composition and disease-related changes. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Improved preservation of mouse intestinal tissue using a formalin/acetic acid fixative Support Protocol: Quantitative tissue analysis using QuPath.

Revealing intact neuronal circuitry in centimeter-sized formalin-fixed paraffin-embedded brain.

Tissue-clearing and labeling techniques have revolutionized brain-wide imaging and analysis, yet their application to clinical formalin-fixed paraffin-embedded (FFPE) blocks remains challenging. We introduce HIF-Clear, a novel method for efficiently clearing and labeling centimeter-thick FFPE specimens using elevated temperature and concentrated detergents. HIF-Clear with multi-round immunolabeling reveals neuron circuitry regulating multiple neurotransmitter systems in a whole FFPE mouse brain and is able to be used as the evaluation of disease treatment efficiency. HIF-Clear also supports expansion microscopy and can be performed on a non-sectioned 15-year-old FFPE specimen, as well as a 3-month formalin-fixed mouse brain. Thus, HIF-Clear represents a feasible approach for researching archived FFPE specimens for future neuroscientific and 3D neuropathological analyses.

CytoLyt fixation impedes insulinoma-associated protein 1 (INSM1) immunoreactivity compared to formalin fixation.

INTRODUCTION: Insulinoma-associated protein 1 (INSM1) is an immunohistochemical marker commonly used to confirm cytomorphological concordant neuroendocrine tumors/carcinomas (NETs/NECs), demonstrating high utility in small samples. Previous reports have suggested comparable INSM1 staining in CytoLyt-fixed cell blocks and formalin-fixed surgical pathology specimens. This study aimed to assess INSM1 immunoreactivity using both fixation methods and investigate potential factors contributing to its variable expression. MATERIALS AND METHODS: A retrospective query was performed (03/31/21-05/31/22) for NET/NEC cases that had both formalin- and CytoLyt-fixed cell blocks. We collected clinical data and reporting of immunostains for each case. INSM1 staining was evaluated in both fixation methods, and reported as positive, negative, or equivocal. Equivocal INSM1 staining was further scored as a percentage of 1%-100% and intensity of weak (faint staining), moderate (darker staining), and strong (dense staining). RESULTS: Our search identified 20 cases from diverse body sites, including mediastinal lymph nodes (40%), pancreas (35%), lung (20%), and porta hepatis lymph nodes (5%). All cases exhibited a widespread positivity (over 90%) in formalin-fixed cell blocks. In contrast, CytoLyt fixed cells showed a negative stain in 65% of cases and 30% exhibited an equivocal positivity. CONCLUSIONS: While INSM1 is previously reported as a sensitive (75%-100%) and specific (82.7%-100%) marker for NET/NECs, our study found a reduced immunohistochemical staining in CytoLyt-fixed cell blocks. Consequently, false negative INSM1 immunohistochemical results in CytoLyt-fixed cell block material may pose a pitfall in the diagnosis of NET/NEC.

Phenolic Determination in Proembryogenic Cell Complexes of Buckwheat Morphogenic Cell Culture with Osmium Tetroxide, Toluidine Blue O Dye, and Iron Chloride.

The study of the localization of secondary metabolites in both plants and the cell cultures on the intravital sections is hampered by the difficulty of obtaining thin, correctly oriented sections. Techniques for fixing tissues in resins allow these difficulties to be overcome. Properly selected tissue fixation techniques allow using different dyes to identify the compound of interest. In addition, some components of tissue fixation can act as fixatives and as a dye for identifying secondary metabolites. For example, osmium tetroxide, which fixes lipids in tissues, stains phenolic compounds black. This paper describes methods for the detection of phenolic compounds in morphogenic callus culture of buckwheat using osmium tetroxide, Toluidine Blue O dye, and ferric chloride as dyes in epoxy resin-embedded cell culture with double fixation of the material and when material fixed in Karnovsky's fixative.

Cadaver preservative properties of a solution composed of honey, ethyl alcohol, liquid paraffin, distilled water and citric acid: Experiments on rabbit cadavers.

The objective of this study is to assess the efficacy of a solution including honey, ethyl alcohol, liquid paraffin, distilled water and citric acid (HEFS) as a preservative for rabbit cadavers, serving as a potential substitute for formaldehyde. The cadavers underwent preservation using three distinct solutions: 10% formalin, 35% alcohol and HEFS. The cadavers were subjected to a total of four sampling events, occurring at 4-month intervals, in order to collect specimens for microanatomical, histological, microbiological, mycological, colourimetric, texture and odour analysis. In terms of hardness, suitability for dissection and joint mobility metrics, the cadavers fixed with HEFS had superior qualities to those fixed with formalin. The fixation quality of HEFS for histological analyses was deemed acceptable, except kidney and intestinal tissues. In texture analysis, differences only in the elasticity parameter (p < 0.05) in the same sampling period. A total of 10 (13.9) bacteria isolates were identified among which, Metasolibacillus meyeri 3 (30%) was predominantly followed by Staphylococcus aureus 2 (20%), Bacillus siamensis, Bacillus subtilis, Pseudarthrobacter oxydans, Bacillus licheniformis, Bacillus subtilis subsp. subtilis with a proportion of 1 (10%), respectively, by both microbiological and molecular analysis. However, no anaerobic bacteria and fungi were isolated. A considerable percentage of the students had the perception that HEFS was appropriate for utilization in laboratory settings due to its absence of unpleasant odours and detrimental impact on ocular and respiratory functions. In conclusion, we consider that HEFS may serve as a viable substitute for formalin solution in the preservation of rabbit cadavers.

Investigation of the use of gelatine-glycerine and gelatine-polyvinyl alcohol mixtures as tissue consistency preservatives in cadavers fixed with modified SEFS solution.

This study aimed to improve the effectiveness of SEFS, a fixing solution composed of soap and ethanol. This was achieved by modifying the formulation of SEFS. Additionally, this study aimed to preserve the consistency of organs by perfusing cadavers with mixtures of gelatine-glycerin (gelatine-Gls) and gelatine-polyvinyl alcohol (gelatine-PVA) through vascular access. The modified SEFS embalmed cadavers were divided into two groups: Group I was treated with gelatine-glycerin, and Group II was treated with gelatine-polyvinyl alcohol and each group comprised of two goats and three rabbits. Over one year, cadavers were objectively assessed for hardness, colour, and joint range of motion. Additionally, the cadavers were subjectively evaluated after dissection and palpation. For the modified SEFS embalmment haptic and optic examinations of the muscles revealed they maintained a vivid colour tone, closely resembling their natural colour. The thoracic organs displayed natural colour, with the lungs retaining their shape without collapse. Notably, the walls of the atrium and ventricles of the heart remained intact without inward collapse. The use of gelatine-PVA yielded better outcomes than gelatine-Gls in preserving the volumes of both chest and abdominal organs. This was particularly evident in the heart, lungs, liver, spleen, and kidney. Overall, the modified SEFS and gelatin-PVA mixtures were superior in maintaining certain properties better than expected from cadavers.

Modified trichrome stain for faster and improved detection of intestinal protozoan parasites.

Permanent stains such as trichrome have better sensitivity but are time-consuming and the fixative includes toxic mercuric chloride. Thus, a newer modification was tested and found to be a superior, faster and safer staining technique for intestinal parasitic detection. Our study lasted 9 months and a single stool sample was collected from each enrolled patient. We evaluated classical trichrome (T1 - using Schaudinn fixative) with newer modifications, which involved different fixatives with mordant combinations (T2 - acetic acid + hydrated aluminium sulphate, T3 - citric acid + copper sulphate hydrate). Conventional PCR targeting Entamoeba histolytica, Giardia lamblia and Cryptosporidium spp. was taken as the reference. Out of 175 stool samples, 25.1% protozoa were identified by wet mount, 24% by each T1 and T2, 25.7% by T3. Statistically, T3 and T2 had higher sensitivity as compared to T1 and wet mount when PCR was used as reference.

Sirka: An alternative to the formalin fixative.

Formalin fixation is the most essential step of routine histopathology practice. During the last few years, various fixatives have been developed for use in histopathology practice as an alternative to formalin, to overcome its side effects on health. Here we have demonstrated an interesting and novel idea of using sirka or sugar cane vinegar as an alternative to the formalin with the adequate result.

Effects of Chemical Fixatives on Kinetic Measurements of Biomolecular Interaction on Cell Membrane.

Understanding the interaction between ligands and membrane proteins is important for drug design and optimization. Although investigation using live cells is desirable, it is not feasible in some circumstances and cell fixation is performed to reduce cell motion and degradation. This study compared the effects of five fixatives, i.e., formaldehyde vapor (FV), paraformaldehyde (PFA), acetone, methanol, and ethanol, on kinetic measurements via the LigandTracer method. We found that all five fixatives exerted insignificant effects on lectin-glycan interaction. However, antibody-receptor interaction is markedly perturbed by coagulant fixatives. The acetone fixation changed the binding of the anti-human epidermal growth factor receptor 2 (HER2) antibody to HER2 on the cell membrane from a 1:2 to a 1:1 binding model, while methanol and ethanol abolished the antibody binding possibly by removal of the HER2 receptors on the cell membrane. The capability of binding was retained when methanol fixation was performed at lower temperatures, albeit with a binding model of 1:1 instead. Moreover, whereas cell morphology does not exert a substantial impact on lectin-glycan interaction, it can indeed modify the binding model of antibody-receptor interaction. Our results provided insights into the selection of fixatives for cell-based kinetic studies.

A cost-effective and efficient ex vivo, ex situ human whole brain perfusion protocol for immunohistochemistry.

BACKGROUND: Chemical fixation of the brain can be executed through either the immersion method or the perfusion method. Perfusion fixation allows for better preservation of the brain tissue's ultrastructure, as it provides rapid and uniform delivery of the fixative to the tissue. Still, not all facilities have the expertise to perform perfusion fixation, with initial high cost and complexity of perfusion systems as the main factors limiting its widespread usage. NEW METHOD: Here we present our low-cost approach of whole brain ex situ perfusion fixation to overcome the aforementioned limitations. Our self-made perfusion system, constructed utilising commercially accessible and affordable medical resources alongside laboratory and everyday items, demonstrates the capability to generate superior histological stainings of brain tissue. The perfused tissue can be stored prior to proceeding with IHC for at least one year. RESULTS: Our method yielded high-quality results in histological stainings using both free-floating cryosections and paraffin-embedded tissue sections. The system is fully reusable and complies with the principles of sustainable management. COMPARISON WITH EXISTING METHODS: Our whole brain perfusion system has been assembled from simple components and is able to achieve a linear flow with a pressure of 70 mmHg corresponding to the perfusion pressure of the brain. CONCLUSIONS: Our ex situ method can be especially useful in research settings where expensive perfusion systems are not affordable or in any field with high time pressure, making it suitable for the field of forensic medicine or pathology in general.

Hair fixative traces on footwear - Establishing a link between footwear and the victim's hair after kicks to the head.

Kicking a person laying on the floor in the head is a crime whose forensic investigation could profit from additional microtraces capable of linking a suspected footwear, and by extension its owner, to the victim and their injuries. The transfer of hair fixatives (hair gel, hair wax, hair spray, hair foam, etc.) represents such a trace and was consequently practically evaluated throughout this study. This study consists of two parts: The first part, the differentiation study, encompasses the visual, and instrumental analysis of a variety of different hair fixatives to determine their analysability and differentiation potential. The visual examination was conducted using alternate light sources and filter lenses. Subsequently, the instrumental analysis was carried out, whereby the focus lay on Fourier Transform Infra-red (FT-IR) spectroscopy and Raman spectroscopy. The second part is comprised of different experiments including a test-transfer and pendulum experiments to assess the process and the potential variables of the transfer of hair fixative traces between hair and fabric shoes during a kick. This helped to determine the effect of the kick strength and the behaviour of differing hair products. Retrieval methods to secure hair fixative traces of footwear and from the hair of a victim were developed. These were subsequently tested out on an acute case example..

Impact of the quality of resected thyroid cancer tissue sample on next-generation sequencing testing.

Activating rearranged during transfection (RET) proto-oncogene alterations can be identified using next-generation sequencing (NGS) of tumor DNA/RNA. We assessed factors associated with NGS (Oncomine Dx Target Test [ODxTT]) success for resected thyroid cancer (TC) specimens, including sample age, processing conditions, and DNA/RNA quality. TC samples were from three Japanese hospitals, with sample age <1-<10 years, fixative 10%/15% neutralized buffered formalin (NBF), and fixation time ≤48 h/>48 h-≤72 h. NGS success rate was defined as the percentage of samples returning validated NGS results (RET fusion-positive/negative [RNA] or RET mutation-positive/negative [DNA], detected using ODxTT). DNA/RNA quality was assessed with indexes based on electrophoresis (DNA/RNA integrity number, DV200 ) and quantitative polymerase chain reaction (DNA/RNA integrity score [ddCq/ΔCq]). NGS success rate (N = 202) was 90%/93% (DNA/RNA) overall, 98%-100% (DNA and RNA) for samples <3 years old, and 91% (DNA and RNA) for samples ≥3-<5 years old fixed in 10% NBF for ≤48 h. Multivariate logistic regression analysis identified ddCq and ΔCq as significant predictors of DNA and RNA NGS success rates, respectively. Quality assessment of nucleic acid extracted from archival tissue samples is important for achieving high NGS success rates in clinical practice, especially for samples ≥3 years old.

Histochemical and morphological evaluation of a glyoxal acid-free fixative.

The application of most chemical fixatives, such as formalin, in the anatomic pathology laboratory requires safety training and hazardous chemical monitoring due to the toxicity and health risks associated with their use. Consequently, the use of formalin has been banned in most applications in Europe; the primary exception is its use in the histology laboratory in lieu of a suitable and safer alternative. Glyoxal based solutions, several of which are available commercially, are the most promising alternative fixatives, because they are based on a mechanism of fixation similar to that of formalin. Unlike formalin, however, glyoxal based solutions do not dissociate from water and therefore do not require ventilation measures such as a fume hood. A primary barrier to the adoption of commercially available glyoxal based solutions is their low pH, which can produce undesirable morphological and antigenic tissue alterations; however, a recently available neutral pH glyoxal product (glyoxal acid free) (GAF) has been developed to mitigate the challenges of low pH. We compared the morphology and histochemistry among tissues fixed in 10% neutral buffered formalin, a commercially available acidic glyoxal product (Prefer), and GAF. Tissues fixed in formalin and Prefer exhibited similar morphology and staining properties; tissues fixed with 2% GAF exhibited deleterious effects.

Correlation of stages of microsporogenesis with bud and anther morphology in pepper genotypes through DAPI staining with different levels of mordant in cytological fixative.

The haploid and doubled haploid plants serve as valuable tools for breeders due to their ability to expedite the mapping of genes of agronomic importance, as well as accelerate the breeding cycle for generation of novel hybrids and improved homogenous varieties. Successful anther/microspore culture largely depends on the use of microspores at appropriate developmental stages at the time of culture, which can be specific for each plant species and genotype. In the present study, we described the visible morphological characteristics of flower buds and anthers at different developmental stages to identify the optimal microspore stage within the anther/buds of two pepper hybrids, Indra and Lakshmi. This information enabled us to predict the suitable microspore stage for successful haploid production. To enhance the visualization of nuclei in the pepper microspores, different concentrations of FeCl3 were employed as a mordant to Carnoy's fixative I, followed by DAPI staining. A clear and distinct nucleus was observed using DAPI staining procedures in the pepper microspores when fixed in Carnoy's solution containing ferric chloride (40-90 µl) as mordant. The use of mordant thus facilitated the efficient cytological analysis of the pepper microspores. Present results indicate that, to achieve efficient haploid production, flower buds with an average length of 4.4 to 5.02 mm for the hybrid Indra and 5.15 to 5.40 mm for the hybrid Lakshmi should be utilized. Additionally, these buds should have a calyx covering approximately 80-90% of the total bud length. We observed that in such buds, microspores are in the late-uninucleate and early binucleate stage which has been reported to be the most conducive stage for androgenesis induction in pepper.

A High-Throughput PIXUL-Matrix-Based Toolbox to Profile Frozen and Formalin-Fixed Paraffin-Embedded Tissues Multiomes.

Large-scale high-dimensional multiomics studies are essential to unravel molecular complexity in health and disease. We developed an integrated system for tissue sampling (CryoGrid), analytes preparation (PIXUL), and downstream multiomic analysis in a 96-well plate format (Matrix), MultiomicsTracks96, which we used to interrogate matched frozen and formalin-fixed paraffin-embedded (FFPE) mouse organs. Using this system, we generated 8-dimensional omics data sets encompassing 4 molecular layers of intracellular organization: epigenome (H3K27Ac, H3K4m3, RNA polymerase II, and 5mC levels), transcriptome (messenger RNA levels), epitranscriptome (m6A levels), and proteome (protein levels) in brain, heart, kidney, and liver. There was a high correlation between data from matched frozen and FFPE organs. The Segway genome segmentation algorithm applied to epigenomic profiles confirmed known organ-specific superenhancers in both FFPE and frozen samples. Linear regression analysis showed that proteomic profiles, known to be poorly correlated with transcriptomic data, can be more accurately predicted by the full suite of multiomics data, compared with using epigenomic, transcriptomic, or epitranscriptomic measurements individually.

Optimization of PAS stain and similar Schiff's based methods for glycogen demonstration in liver tissue.

Demonstration of glycogen in tissue holds considerable diagnostic relevance across various pathological conditions, particularly in certain tumors. The histochemical staining of glycogen using methods utilizing Schiff's reagents is subject to influences arising from the type of fixative, fixation temperature, and oxidizing agents employed. This study aimed to assess diverse fixatives, fixation temperatures, and oxidizing agents, each with variable treatment durations, in conjunction with Schiff's reagent for optimal glycogen demonstration. Paraffin blocks derived from a rabbit's liver served as the experimental substrate, encompassing 340 paraffin sections subjected to different procedures. For tissues fixed at 4 °C, good staining outcomes, as determined by the periodic acid-Schiff (PAS) stain, were observed with 10% neutral buffered formalin (NBF), 80% alcohol, and Bouin's solution. Tissues fixed at room temperature (RT) demonstrated good PAS staining results with both 10% NBF and 80% alcohol. Notably, other oxidizing agents exhibited poor outcomes across all fixatives and fixation temperature, with two exceptions, as satisfactory staining results were obtained when using 5% chromic acid. Consequently, Both 10% NBF and 80% emerge as preferred fixatives of choice for glycogen demonstration when coupled with PAS stain. It is noteworthy that Bouin's solution could also provide good outcomes when fixation occurred at 4 °C.

Ethanol, Carnoy, and paraformaldehyde as fixative solutions for histological evaluation of preantral follicles in equine ovarian tissue.

The most adequate fixative solution for equine ovarian tissue is still to be determined as a tool to evaluate the improvement of methodological studies in assisted reproductive techniques and fertility preservation. This study aimed to evaluate a short-time ethanol 70% (ST-EtOH, 45 min) exposure as an alternative fixative compared with two classically fixatives [Carnoy's (CAR) solution and paraformaldehyde 4% (PFA)] at different fixation times (6 h, 12 h). The end points evaluated were morphology and classes of preantral follicles, follicular and stromal cell densities, and follicular and oocyte nuclear diameters in equine ovarian tissue. Ovaries (n = 6) from ovariectomized young mares were fragmented (3 × 3 × 1 mm; 20 fragments/ovary) and fixed in the tested treatments. Overall, a total of 11,661 preantral follicles were evaluated in 1444 histological slides. The ST-EtOH similarly preserved the preantral follicle morphometry and stromal cell density compared to the PFA fixative, regardless of the exposure time. Nonetheless, the CAR fixative solution had the greatest percentage of normal preantral follicles and the highest stromal cell density among all treatments. In conclusion, Carnoy's solution must be preferred compared with ST-EtOH and PFA fixatives for studies concerning the cellular morphology of equine ovarian tissue. Moreover, ST-EtOH fixative is a good alternative for equine ovarian tissue when a quick histological evaluation is required instead of more time-consuming and expensive techniques. Additional studies concerning the impact of different fixatives on the ultrastructure of cellular populations and their compatibility with IHC and molecular techniques in equine ovarian tissue are warranted.

Gelatin Zymography Can Be Performed on Fixed Brain Tissue.

Gelatin zymography is widely used to detect gelatinase activity, which is performed on unfixed tissue because it is assumed that fixation inactivates enzymes. However, using fixed tissues has several advantages over using fresh tissues for such prevention of tissue decay, thereby preserving the proteins as well as the morphology and structure of the specimens. In this study, we investigated the effects of the four commonly used fixatives (ethanol, acetone, zinc-based fixative (ZBF), and paraformaldehyde (PFA)) on the gelatinolytic activity in mouse brain tissue. Multiple protocols were employed to extract proteins from the fixed brain tissue. Western blotting and in-gel zymography (IGZ) were used to detect the gelatinase proteins and gelatinolytic activity of the extractions, respectively. In situ zymography (ISZ) revealed that ethanol, acetone, ZBF, and short-time PFA fixation did not inhibit gelatinolytic activity. Neither 1% Triton + 1 M NaCl nor 10% DMSO + 1 M NaCl was effective in extracting proteins from ethanol-, acetone-, ZBF-, or PFA-fixed brain tissues. However, 8 M urea + 4% CHAPS effectively extracted gelatinase proteins from ethanol- and acetone-fixed tissues while retaining the gelatinolytic activity. 2% SDS effectively extracted gelatinase proteins from ethanol-, acetone-, and ZBF-fixed tissues while retaining the gelatinolytic activity. Although 2% SDS + heating extracted gelatinase proteins from ethanol-, acetone-, ZBF-, and even long-term PFA-fixed tissues, the gelatinolytic activity was not retained. Our findings suggest that both ISZ and IGZ can be performed on fixed brain tissue, which is anticipated to be an improvement over the conventionally used gelatin zymography methods. (J Histochem Cytochem 71: 481-493, 2023).

Immunofluorescence protocol for localizing protein targets in brain tissue from diverse model and non-model mammals.

Previous immunostaining protocols are highly specific for model organisms and often not suitable for diverse specimens that are non-perfused and over-fixed (i.e., tissues sitting in fixatives for months/year). Here, we present an immunofluorescence protocol for localizing protein targets in brain tissue from 11 model and non-model mammals. We describe preparation of both fresh and fixed tissues including steps for deparaffinization, fixation, and cryoprotection. We then detail immunofluorescence procedures including antigen retrieval, reducing autofluorescence, nuclear staining, mounting, and image collection.

Comparative evaluation of the effect of three types of fixatives (formalin, Bouin and Carnoy) on histomorphological features of various viscera.

Tissue shrinkage is one of the problems in preparing tissue sections. This study compares the use of 10% formalin, Bouin and Carnoy as fixatives on several mouse tissues to determine histomorphological features. In this experimental study, liver, kidney, heart, lung, testicle, spleen, brain and cartilage tissues were isolated from five BALB/c mice. Then, they were fixed with three types of fixatives. After dehydrating, clarifying and embedding, all samples were stained with haematoxylin and eosin. Then, the tissue structure of the viscera was evaluated qualitatively. The results showed that each fixative is more suitable for evaluating a specific part of the tissue. However, relative shrinkage appeared in the tissue sections fixed with 10% Formalin, (1) in the heart as spaces between muscle fibre bundles, (2) in the liver as the dilation of the liver sinusoidal spaces, (3) in the kidney tissue as the expansion of the lumens of the convoluted proximal and distal tubules, (4) in the spleen as open spaces inside the red and white pulps and (5) in the brain as an increase in the space between the cells of the granular and pyramidal cell layers of the cortex. In tissues that were soft and fragile, such as testis, liver and brain, Bouin's fixative was more suitable. Carnoy's fixative was more suitable for the spleen and kidney tissue. Based on the study results, formalin and Bouin were more suitable for heart and cartilage tissue. Considering that in the histopathological evaluation both the cytoplasm and the nucleus are evaluated, it is suggested to choose the fixative suitable for the type of tissue.