Staining blindly: an update on coloring techniques for fecal smears in parasitology: a scoping review

Dye application for parasite highlighting in the Ova and Parasite exam is a common practice in parasitology diagnosis. Methods: A scoping review investigated how staining solutions interact with parasite structures. After screening 1334 papers, 35 met eligibility criteria. Results: Differentiating background from foreground in the fecal smear under light microscopy is the core of the research on this topic. Refractivity, unevenness of staining, size and temperature were explored to enhance staining protocols. Cryptosporidium spp. and Microsporidia were the main studied species. Conclusion: Studies on diagnostic efficacy outperform those that elucidate the physical-chemical interaction between dyes and parasites. An alternative approach involves technicians using computational tools to reduce subjectivity in fecal smear interpretation, deviating from conventional methods.

Evaluating color stability and enamel surface roughness following resin infiltration treatment

OBJECTIVE

To assess the impact of resin infiltration treatment on enamel color stability and surface roughness after simulating daily exposure to coffee stains and regular toothbrushing with standard toothpaste.

MATERIALS AND METHODS

In this in vitro study, we utilized 47 caries-free human enamel specimens, which were divided into two distinct groups. The teeth in the study group underwent artificial demineralization, Icon resin infiltration, and polishing, while the control group received only polishing. Following this, all teeth from both groups were regularly immersed in freshly brewed coffee for 15 min, twice daily, over a span of 30 days. After each staining session, the teeth underwent 10 heavy circular strokes using a soft toothbrush and standard toothpaste. Color changes were measured on Days 1 and 30 using a spectrophotometer. The L*, a*, b* color system defined by the International Commission on Illumination was used to assess the changes. Surface roughness was evaluated at baseline and after 30 days using a 3D surface Metrology Microscope.

RESULTS

After 30 days of immersion in coffee, both the study and control groups showed significant changes in color. However, differences were statistically significant between groups for "L" and "a" parameter but not for "b." The overall color change in the study group was higher than the control group. There were no significant differences in surface roughness within or between the groups before and after staining and brushing.

CONCLUSIONS

Resin infiltration leads to a significant increase in staining compared to untreated enamel. These staining properties should be taken into account when making clinical decisions regarding the treatment of white spot lesions.

Assessment of colour modifications in two different composite resins induced by the influence of chlorhexidine mouthwashes and gels, with and without anti-staining properties: An in vitro study

OBJECTIVES

Chlorhexidine (CHX)-based products are the most effective chemical agents used in plaque control and oral disinfection. One of their side effects is tooth and restoration staining. For this reason, CHX products with anti-discolouration systems (ADS) have been developed. The aim of this in vitro study was to compare different CHX-based products (gel and mouthwash) with or without ADS in composite colour modification.

METHODS

Two hundred specimens were created, 100 of which were made of packable composite and 100 of flowable composite. After 24 h, colour coordinates (L*, a*, b*, C*, h°) were recorded using a spectrophotometer (T0). Then, all samples were subjected to a CHX/tea staining model and immersed in human saliva for 2 min. Composite specimens were divided in 10 groups (N = 20). Control groups (PC, FC) were soaked in distilled water and test groups (PG, PGads, FG, FGads, PM, PMads, FM and FMads) were immersed in CHX-based solutions or brushed with CHX gel. Then the cycle was repeated 6 times, and colour differences (ΔEab and ΔE00 ) were finally calculated.

RESULTS

Through flowable composites, FC and FG showed the highest colour differences, respectively ΔEab  = 3.48 ± 1.0, ΔE00  = 2.24 ± 0.6 and ΔEab  = 2.95 ± 1.3, ΔE00  = 1.53 ± 0.6. In the composite groups instead, PM and PMads showed the highest colour differences, respectively ΔEab  = 2.78 ± 1.3, ΔE00  = 1.94 ± 0.8 and ΔEab  = 2.71 ± 1.4, ΔE00  = 1.84 ± 0.9.

CONCLUSIONS

CHX-containing products are able to cause stains on restorative composite materials. Discolouration is more likely to occur in flowable composites than packable composites, and ADS-containing products cause fewer pigmentations than CHX products without ADS. Packable composites showed more staining after mouthwash treatment, whereas flowable composites underwent higher discolouration after treatment with gels.

Comparative in situ hybridization protocols in zebrafish

In situ hybridization is a commonly used technique in molecular biology to assess the temporal and spatial expression of a given gene. As a long and labor-intensive protocol, double in situ hybridization, which detects two genes in series, is challenging and can require a lot of troubleshooting. Optional additives, polyvinyl alcohol and dextran sulfate, were tested in a standard in situ hybridization protocol and several colorimetric stain pairings using double in situ hybridization in zebrafish embryos. Optional additives can improve staining time and reduce nonspecific background. Nitro-blue tetrazolium chloride/5-bromo-4-chloro-3-indolyl phosphate (BCIP) + Fast Red/BCIP was the most effective stain pairing. As a proof-of-concept, this work shows that Cabin1 and atoh1b are expressed in distinct regions of the developing zebrafish brain.

A comparison of colorimetric stains and protocols in double in situ hybridization in whole-mount zebrafish embryos.

External quality assessment by European mycobacterial laboratories: results of AFB microscopy and identification rounds

We analyzed mycobacterial stain, culture and identification EQA data from altogether 134 laboratories in 15 mainly European countries over a 4-year period. The aim was to get an overview of the performance and methods and identify diagnostic challenges. The overall success rates for staining and identification were 94% and 91%. The false negative rate for staining was significantly higher for the medium positive than the strong positive slides (11% vs 4%). The false positive rate on negative slides was 10%, indicating contamination issues. The overall success of M. tuberculosis detection was high with error rates ranging from 0.7% to 1.2%. Pre- or postanalytical errors accounted for most of the unsuccessful responses. The detection of nontuberculous mycobacteria (NTM) was less consistent; accurate species identification depended on the assays used. Only 19% of participants performed species level identification for NTMs, 47% detected the presence NTMs while 21% focused on ruling out TB.

Exploring Honeybee Abdominal Anatomy through Micro-CT and Novel Multi-Staining Approaches

Simple Summary

Apis mellifera or western honeybees are insects belonging to the Order Hymenoptera and the most important pollinators worldwide with great implications in natural biodiversity and agriculture due to their importance in pollination and honey production. The characterization of honeybee anatomy with precise tools will allow a better comprehension of the physiology of these insects under different biological conditions. Here, we employed Micro-computed tomography and novel staining methods to define the morphoanatomical characteristics of the worker honeybee abdomen. We defined the 3D and 2Ds structures of the midgut and hindgut and discovered a new cell type called ventricular telocyte, with possible roles in honeybee epithelium maintenance. Overall, we propose that this method will be useful for further investigation of the structure of the honeybee abdomen under a wide variety of environmental conditions.

Abstract

Continuous improvements in morphological and histochemical analyses of Apis mellifera could improve our understanding of the anatomy and physiology of these insects at both the cellular and tissue level. In this work, two different approaches have been performed to add new data on the abdomen of worker bees: (i) Micro-computed tomography (Micro-CT), which allows the identification of small-scale structures (micrometers) with adequate/optimal resolution and avoids sample damage and, (ii) histochemical multi-staining with Periodic Acid-Schiff-Alcian blue, Lactophenol-Saphranin O and pentachrome staining to precisely characterize the histological structures of the midgut and hindgut. Micro-CT allowed high-resolution imaging of anatomical structures of the honeybee abdomen with particular emphasis on the proventriculus and pyloric valves, as well as the connection of the sting apparatus with the terminal abdominal ganglia. Furthermore, the histochemical analyses have allowed for the first-time description of ventricular telocytes in honeybees, a cell type located underneath the midgut epithelium characterized by thin and long cytoplasmic projections called telopodes. Overall, the analysis of these images could help the detailed anatomical description of the cryptic structures of honeybees and also the characterization of changes due to abiotic or biotic stress conditions.

Histochemical characterization of bone and cementum using modified gallego's iron fuschin stain and van gieson stain and its application in fibro-osseous lesions

Objectives

Fibro-osseous lesions (FOLs) of the jaws exhibit an overlapping histomorphologic spectrum with respect to nature of calcifications. Sometimes these calcifications may be difficult to characterize as bone and cementum on routine Hematoxylin and Eosin (H&E) staining. This causes difficulty in assessing the origin and diagnosis of these lesions. Thus the study aimed to characterize bone, cementum, and hard tissue components in FOLs using special stains.

Method

The study included a histochemical evaluation of 20 samples of bone and cementum and 12 cases each of fibrous dysplasia (FD) and ossifying fibroma (OF). Three consecutive sections of each tissue were stained with H and E, modified Gallego's iron fuschin stain and Van Gieson stain. H and E and modified Gallego's iron fuschin stained sections were analyzed under light microscope whereas Van Gieson stained section was analyzed under polarizing microscope.

Results

It was found that cementum stained red and bone stained greenish-yellow in color. The calcifications seen in fibrous dysplasia stained greenish-yellow in color. Three cases of OF showed greenish-yellow calcifications and nine cases showed reddish calcifications. Polarization study of bone showed lamellar pattern and tooth cementum showed quilt pattern. Four cases of FD showed lamellar pattern and eight cases showed haphazard pattern. In OF, three cases showed lamellar pattern and nine cases quilt pattern.

Conclusion

Calcifications having lamellar pattern and greenish-yellow color suggest their osteogenic origin thus having aggressive nature and requiring aggressive treatment. Calcifications having quilt pattern and reddish color suggest periodontal ligament origin thus having less aggressive behavior and less extensive treatment.

3D-Non-destructive Imaging through Heavy-Metal Eosin Salt Contrast Agents

Conventional histology is a destructive technique based on the evaluation of 2D slices of a 3D biopsy. By using 3D X‐ray histology these obstacles can be overcome, but their application is still restricted due to the inherently low attenuation properties of soft tissue. In order to solve this problem, the tissue can be stained before X‐ray computed tomography imaging (CT) to enhance the soft tissue X‐ray contrast. Evaluation of brominated fluorescein salts revealed a mutual influence of the number of bromine atoms and the cations applied on the achieved contrast enhancement. The dibromo fluorescein barium salt turned out to be the ideal X‐ray contrast agent, allowing for 3D imaging and subsequent complementing counterstaining applying standard histological techniques.

Efficacy evaluation of rubber cup and air polishing techniques using glycine in plaque and stain removal - A clinical trial

Background:

Researchers have proved Glycine to be safe, less abrasive, sweet and comfortable for patients. It is beneficial in removing plaque as well as stains. The present study aims to compare the plaque and extrinsic stain removal efficacy of the air-polishing device and rubber cup prophylaxis technique along with a comparative evaluation of the gingival trauma caused by both the techniques.

Method:

This split-mouth randomized clinical trial was conducted on a total of 60 subjects in half of whom, left side was assigned to Glycine powder air polishing and the right side to rubber cup prophylaxis with (Glycine powder) and vice versa in the other half. All the subjects had their calculus removed one month prior to the intervention. Plaque index, Stain index and Trauma index were recorded and statistical analysis was done.

Results:

Both the techniques (RCP and AP) demonstrated a significant reduction in plaque and stains within their respective groups, but revealed non-significant differences between the study groups. Gingival trauma was found to be significantly higher in case of AP group. Rubber cup technique was preferred over air polishing by the subjects.

Conclusion

The data indicates that both the techniques were equally beneficial for plaque and stain removal, but rubber cup polishing technique has an advantage over the air polishing technique.

Parasitic necrotizing pneumonia in an immunocompetent patient in United States

A 59-year-old Baltimore native female, with a history of asthma and no history of travel outside of the USA, presented with productive cough and shortness of breath. Computed tomography scan showed left upper lobe consolidation of the lung with multiple tiny cavitations. She was empirically treated without improvement. Later, strongyloides were found in the sputum gram stain and she was treated with ivermectin. Pulmonary strongyloidiasis has been mainly described in patients who are immunosuppressed and have a history of travel to endemic areas, both of which were absent in our patient. Our case underlines the importance of considering strongyloides necrotizing pneumonia as a differential diagnosis of community-acquired pneumonia even in immunocompetent patients in the USA, especially if not responding to empiric treatment.

Effect of Green, Tulsi, and Areca Teas on the Color Stability of Two Composite Resin Materials - an in vitro Spectrophotometric Analysis

Objective

To compare the effect of Green, Tulsi, and Areca teas on the color stability of two composite materials on the 30th and 60th days.

Materials and Methods

Two light cure composite restorative materials, Brilliant EverGlow (Group 1) and Brilliant NG, (Group 2) with different resin and filler characteristics were selected. The test solutions selected were Green tea, Tulsi tea, Areca tea, and artificial saliva (control group). In total, 104-disc shaped specimens were fabricated using a custom made brass mold as per the manufacturer instructions. All specimens were put in storage for rehydration and complete polymerization at 37°C in distilled water for 24 hours. Specimens of each composite material were randomly divided into four subgroups of 13 samples. Tea solutions were freshly prepared, and specimens were immersed in the respective solutions every day for 15 minutes for 60 days. Specimens were stored in artificial saliva after the immersion regimen. The color evaluation was done before immersion, on the 30th and 60th day, using a digital reflectance spectrophotometer.

Results

At 30 days, Group 1 specimens immersed in Areca and Green teas showed significantly higher mean values than those in control and Tulsi tea. At 60 days in Group 1, specimens in Areca tea showed significantly higher mean value, followed by Green tea, Tulsi tea, and control. At 30 and 60 days in group 2, specimens in control had significantly lower mean values than other tea preparations. Group 1 showed a higher mean difference in ΔE than Group 2 specimens immersed in Green and Areca teas at 30 days (P=0.001 and 0.001) and 60 days (P=0.001 and <0.001), respectively.

Conclusion

All herbal tea preparations exhibited staining potential, which increased over time, and Areca tea showed the highest staining potential. Understanding the staining potential of newer tea preparations on recent composite materials helps the clinician to choose the right restorative materials.

Independent and Distinct Associations of FABP4 and FABP5 With Metabolic Parameters in Type 2 Diabetes Mellitus

Objective: Among fatty acid-binding proteins (FABPs), secreted forms of FABP4 and FABP5, which are expressed in adipocytes and macrophages, act as bioactive molecules. We investigated concentrations of FABP4 and FABP5 in patients with type 2 diabetes mellitus. Methods: As a sub-analysis study of the Randomized Evaluation of Anagliptin vs. Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial, 256 patients (male/female: 146/110, age: 68 ± 10 years) with type 2 diabetes mellitus and dyslipidemia who were receiving statin therapy were recruited. Patients who had been treated with a thiazolidinedione were excluded. Results: Several drugs which may modulate FABP4 levels including statins, dipeptidyl peptidase-4 inhibitors and angiotensin II receptor blockers had been administered in 100, 81, and 51% of the recruited patients, respectively. The level of FABP4, but not that of FABP5, was significantly higher in females than in males. Multivariable linear regression analysis demonstrated that waist circumference (β = 0.21), estimated glomerular filtration rate (β = -0.31), triglycerides (β = 0.16), and FABP5 (β = 0.39) were independent predictors of FABP4 level after adjusting age and sex. On the other hand, FABP5 level was independently associated with levels of FABP4 (β = 0.57) and high-density lipoprotein (HDL) cholesterol (β = -0.12). Conclusions: Concentrations of FABP4 and FABP5 are independent predictors of each other in patients with type 2 diabetes mellitus. There are distinct independent associations of FABP4 with renal dysfunction, adiposity and hypertriglyceridemia and there is a distinct independent association of FABP5 with a low HDL cholesterol level in type 2 diabetic patients with dyslipidemia at high risks for cardiovascular disease who are receiving statin therapy.

Solving the problem with stannous fluoride: Extrinsic stain

BACKGROUND

This article highlights a stabilized stannous fluoride (SnF₂) dentifrice that, in addition to being efficacious against caries, gingivitis, and dentin hypersensitivity, demonstrates high-performing stain prevention and removal efficacy.

METHODS

An in vitro stain prevention model evaluated the efficacy of Colgate Total^SF containing 0.454% SnF₂ and 1% zinc phosphate compared with Crest Pro-Health Whitening Power (The Procter & Gamble Company) and a nonabrasive SnF₂ gel. L*, a*, and b* values were measured to assess whiteness comparing untreated and stained teeth, and with statistical analysis. A stain removal clinical study was conducted as a randomized, double-blind, 2-cell, parallel-group design using Colgate Total^SF and nonwhitening regular fluoride toothpaste. Participants were instructed to brush twice daily for 6 weeks and were examined for Lobene Composite Stain Index scores, with statistical analysis used at a significance of P < .001.

RESULTS

In an in vitro stain prevention study, Colgate Total^SF performed 26% and 35% better than a competitor paste and nonabrasive SnF₂ gel, respectively. In a clinical study, Colgate Total^SF use showed statistically significant extrinsic tooth stain reductions by 17.5% (3 weeks) and 27.8% (6 weeks) relative to regular fluoride toothpaste. No adverse effects were reported.

CONCLUSIONS

The results indicate that the stabilized Colgate Total^SF performed statistically better than other SnF₂ pastes in an in vitro study, and statistically better than a regular fluoride toothpaste in a clinical study.

PRACTICAL IMPLICATIONS

Colgate Total^SF offers an SnF₂-based therapeutic dentifrice with notable performance in stain prevention and removal.

Coloring plastinated specimens

In the early days of plastination, plastinate Color was the usual grey/brown familiar to formalin-fixed biological specimens. Initially, trials with Kaiserling's, Klotz, Jore's and McCormick's fixative solutions were disappointing. Vascular injections with Colored epoxy were a great breakthrough in the 1980s. Biodur AC10^® stain was the first stain of note to be applied to gross specimens to be plastinated and was applied in the last acetone bath. As plastination became more popular, specimen Color became an important and necessary aspect. Reactivation of the normal Color of red blood cells within a formalin-fixed specimen was introduced as a mechanism to restore Color to plastinated specimens. Painting of plastinated vessels was tried with some success, and finally, a superior new proprietary type of silicone coloration was developed. More recently, a versatile red pigment stain was developed. All of these have added aesthetically to the plastination processes and will certainly be a reality in the years to come. The various methodologies to Color plastinates are presented. Time will tell how effective these may or may not be.

Stain removal and whitening by baking soda dentifrice: A review of literature

BACKGROUND

Tooth discoloration may be caused by intrinsic or extrinsic stains or a combination of both. There are 2 major approaches to removing the stains, including the chemical mechanism using peroxides for tooth bleaching and the mechanical mechanism using abrasives in prophylactic pastes and dentifrices to remove stains, resulting in a whitening effect. Attempts have also been made to add a low concentration of peroxides to dentifrices to enhance their abrasive cleaning to remove tooth stains.

TYPES OF STUDIES REVIEWED

This article provides a review of both in vitro and clinical studies on stain removal and whitening effect of dentifrices containing sodium bicarbonate (baking soda). In recent years, whitening dentifrices have become popular because of little additional effort for use, ease of availability, low cost, and accumulated evidence of clinical efficacy and safety in the literature. Advances in research and technology have led to innovative formulations of dentifrices using baking soda as the sole abrasive or a component of an abrasive system. Baking soda is biologically compatible with acid-buffering capacities, antibacterial at high concentrations, and has a relatively lower abrasivity.

CONCLUSIONS

The evidence available in the literature indicates that baking soda-based dentifrices are effective and safe for tooth stain removal and consequently whitening. A number of clinical studies have also shown that baking soda-based dentifrices are more effective in stain removal and whitening than some non-baking soda-containing dentifrices with a higher abrasivity. So far, research efforts have mainly focused on stain removal and tooth-whitening efficacy and clinical safety of baking soda dentifrices used with manual toothbrushes, with only a few studies investigating their effects using powered toothbrushes, for which further research is encouraged.

PRACTICAL IMPLICATIONS

As part of a daily oral hygiene practice, baking soda-based dentifrice is a desirable, alternative or additional measure for tooth stain removal and whitening.

Overview of cerebrospinal fluid cytology

Cerebrospinal fluid (CSF) cytology, i.e., the cytologic evaluation of its cellular composition, forms an integral part of the neurologist's armamentarium. Total and differential cell counts provide important first information across a spectrum of pathologic conditions involving the central nervous system and its coverings. CSF samples require immediate processing, ideally within 1 hour from collection. Upon centrifugation cytology is commonly assessed on May-Grunwald-Giemsa stains. Several additional stains are available for the identification of infectious agents such as bacteria or fungi, or the further specification of neoplastic cells by immunocytochemistry. The evaluation warrants familiarity with cytologic characteristics of cells across normal and diseased states. In normal CSF, lymphocytes and monocytes are encountered. A predominance of neutrophil granulocytes suggests bacterial meningitis and prompts search for intracellular bacteria. In contrast, in viral and chronic infections lymphocytes and monocytes prevail. Upon activation lymphocytes typically enlarge and eventually differentiate into plasma cells. Similarly, monocytes differentiate into macrophages that clear cellular debris. Macrophages that contain fragments of erythrocytes or hemoglobin degradation products are referred to as erythro- or siderophages, both of which indicate prior subarachnoid hemorrhage. Likewise, the detection of tumor cells is specific for neoplastic meningitis, although false-negative CSF cytologies are frequent. In summary, detailed morphologic workup of CSF samples provides valuable diagnostic information and is mandated in all cases with elevated cell count, computed tomography-negative suspected subarachnoid hemorrhage, and neoplastic meningitis. In all cases it needs to be interpreted in the clinical context and complements other clinical and laboratory findings.

Documentation of postmortem changes in salivary gland architecture and staining characteristics

CONTEXT

Estimation of time passed since death continues to be a major problem for the forensic pathologist and its determination plays an important and vital role in medico-legal cases. The histological studies on various tissues after death have been mostly confined to single organ or tissue by individual workers at different atmospheric conditions.

AIMS

The aim of this study is to determine the best rehydrating solution for dehydrated tissues in postmortem examination.

SETTINGS AND DESIGN

This study was specific to salivary gland tissues and certain pattern of changes were determined during postmortem time intervals using hematoxylin and eosin stain and special stains like mucicarmine and alcian blue.

MATERIALS AND METHODS

The study was divided into two groups. (1) Group A: Normal tissue samples (twenty normal salivary gland tissue samples left without fixation for varying periods of time). (2) Group B: Control group (twenty normal salivary gland tissue samples immediately fixed in formalin). The three different rehydrating agents used in this study were glycerol, normal saline and modified Ruffer solution.

STATISTICAL ANALYSIS USED

Not required.

RESULTS

Modified Ruffer solution is the best when compared to glycerol and normal saline for rehydration of dehydrated tissues.

CONCLUSIONS

Thus in our study we conclude that the tissue which had been dehydrated at the crime scene for a fairly long period showed better rehydration with modified Ruffer solution and yield good cellular and nuclear details.

Diagnosis of dry eye disease and emerging technologies

Dry eye is one of the most commonly encountered problems in ophthalmology. Signs can include punctate epithelial erosions, hyperemia, low tear lakes, rapid tear break-up time, and meibomian gland disease. Current methods of diagnosis include a slit-lamp examination with and without different stains, including fluorescein, rose bengal, and lissamine green. Other methods are the Schirmer test, tear function index, tear break-up time, and functional visual acuity. Emerging technologies include meniscometry, optical coherence tomography, tear film stability analysis, interferometry, tear osmolarity, the tear film normalization test, ocular surface thermography, and tear biomarkers. Patient-specific considerations involve relevant history of autoimmune disease, refractive surgery or use of oral medications, and allergies or rosacea. Other patient considerations include clinical examination for lid margin disease and presence of lagophthalmos or blink abnormalities. Given a complex presentation and a variety of signs and symptoms, it would be beneficial if there was an inexpensive, readily available, and reproducible diagnostic test for dry eye.

Improved gold chloride staining method for anatomical analysis of sensory nerve endings in the shoulder capsule and labrum as examples of loose and dense fibrous tissues

Consistency in gold chloride staining is essential for anatomical analysis of sensory nerve endings. The gold chloride stain for this purpose has been modified by many investigators, but often yields inconsistent staining, which makes it difficult to differentiate structures and to determine nerve ending distribution in large tissue samples. We introduce additional steps and major changes to the modified Gairns' protocol. We controlled the temperature and mixing rate during tissue staining to achieve consistent staining and complete solution penetration. We subjected samples to sucrose dehydration to improve cutting efficiency. We then exposed samples to a solution containing lemon juice, formic acid and paraformaldehyde to produce optimal tissue transparency with minimal tissue deformity. We extended the time for gold chloride impregnation 1.5 fold. Gold chloride was reduced in the labrum using 25% formic acid in water for 18 h and in the capsule using 25% formic acid in citrate phosphate buffer for 2 h. Citrate binds gold nanoparticles, which minimizes aggregation in the tissue. We stored samples in fresh ultrapure water at 4° C to slow reduction and to maintain color contrast in the tissue. Tissue samples were embedded in Tissue Tek and sectioned at 80 and 100 μm instead of using glycerin and teasing the tissue apart as in Gairns' modified gold chloride method. We attached sections directly to gelatin subbed slides after sectioning with a cryostat. The slides then were processed and coverslipped with Permount. Staining consistency was demonstrated throughout the tissue sections and neural structures were clearly identifiable.

Concentration-dependent specimen shrinkage in iodine-enhanced microCT

Iodine potassium iodide (I2 KI) solution can be employed as a contrast agent for the visualisation of soft tissue structures in micro-computed tomography studies. This technique provides high resolution images of soft tissue non-destructively but initial studies suggest that the stain can cause substantial specimen shrinkage. The degree of specimen shrinkage, and potential deformation, is an important consideration when using the data for morphological studies. Here we quantify the macroscopic volume changes in mouse skeletal muscle, cardiac muscle and cerebellum as a result of immersion in the common fixatives 10% phosphate-buffered formal saline, 70% ethanol and 3% glutaraldehyde, compared with I2 KI staining solution at concentrations of 2, 6, 10 and 20%. Immersion in the I2 KI solution resulted in dramatic changes of tissue volume, which were far larger than the shrinkage from formalin fixation alone. The degree of macroscopic change was most dependent upon the I2 KI concentration, with severe shrinkage of 70% seen in solutions of 20% I2 KI after 14 days' incubation. When using this technique care needs to be taken to use the lowest concentration that will give adequate contrast to minimise artefacts due to shrinkage.

A method for staining nematode secretions and structures

Secretions from amphids, phasmids, and excretory system were stained by incubating nematodes in 0.1% coomassie brilliant blue G-250 in 40% aqueous methanol containing 10% acetic acid on slides with coverslips sealed with nail polish or Zut. Nematodes incubated in this staining solution usually produced copious amounts of secretions from their amphids and excretory pore. Phasmids also stained dark blue, enabling them to be easily observed. Other biological dyes stained these secretions or were useful for differentiating specific morphological features of nematodes.