Evaluation and comparison of the efficacy of coconut oil as a clearing agent with xylene

Background

Xylene is a routinely used clearing agent in histopathology. It is potentially toxic and flammable in nature. Histotechnicians are routinely exposed to this hazardous chemical. Because xylene is used so pervasively in histopathology, it has always been a concern for pathologists and laboratory workers, as its regular and prolonged exposure have serious health effects. Considering its toxicity, different biocompatible xylene substitutes have been evaluated.

Aim and Objectives

This study was conducted to evaluate the efficacy of coconut oil as a clearing agent and compare with xylene.

Materials and Methods

Two equal halves of 45 soft-tissue specimens were processed simultaneously in xylene and coconut oil as clearing agents. The xylene-treated specimens and coconut oil-treated specimens were checked for gross and histological features, and a comparison was done between the two groups.

Results

Significant shrinkage was noted in xylene-treated specimens compared to that in coconut oil-treated specimens. No difference was found in either of the sections when checked for staining quality, overall morphological features and cellular details.

Conclusion

It may be substituted for xylene without loss of information.

Tissue Processing

Tissue processing is the technique by which fixed tissues are made suitable for embedding within a supportive medium such as paraffin, and consists of three sequential steps: dehydration, clearing, and infiltration. In most clinical and research settings, tissue processing is accomplished using an automated tissue processor, with or without microwave-assistance. To ensure high-quality results, processing protocols should be tailored to tissue size and composition by modifying variables such as reagents used and the timing of the various steps. Herein, we provide an overview of tissue processing theory and outline a basic tissue processing method for use with a conventional automated fluid transfer/enclosed processor. The principles described will assist readers in optimizing tissue processing for their own projects.

Paraffin-embedding for large volume bio-tissue

Acquiring ultrahigh-resolution three-dimensional images of large-volume tissues non-human primate tissues was an enormous challenge. Given the preservation of structure and excellent sectioning property, formalin-fixed paraffin-embedding method had an enormous potential for three-dimensional reconstruction of fine structures, based on the very thin histological sections and optical images. However, maintaining the structure uniformly in large-volume tissues was difficult during the complex processes. In this study, we presented a detailed protocol for the whole mouse, rat, rabbit brains, and even for the macaque hemisphere. The entire protocol took about 2–30 days to complete for a large sample, including fixation, dehydration, clearing, wax immersion and embedding. In addition, it could be applied to other species and organs, while the embedding processes depended on the size and the type of organs. This method had wide applicability to serve as a baseline for further technique development.

Catalytic pyrolysis of lignocellulosic bio-packaging (jute) waste – kinetics using lumped and DAE (distributed activation energy) models and pyro-oil characterization

The present study concentrates on the catalytic pyrolysis of a waste bio-packaging material, namely, jute, under iso-thermal and non-isothermal conditions using a 50 mm diameter and 164 mm long semi-batch pyrolyzer and a TGA set-up, respectively.

Intra-molecular enantiomerism in R-(+)-Limonene as evidenced by the differential bond polarizabilities

We propose an algorithm to obtain the differential bond polarizabilities from the Raman and Raman optical activity (ROA) spectral intensities. The signs of the differential bond polarizabilities of R-Limonene demonstrate that there is intra-molecular enantiomerism in its six membered ring structure. That is, the signs of the differential bond polarizabilities around the six membered ring are inversed under an intra-molecular mirror reflection. This is similar to what happens in the right and left handed chiral isomers under a mirror conversion.

Histology without xylene

After the hazardous effects of xylene became indisputable in the 1970s, many potential substitutes became available, some with as many if not more hazards. This article discusses the inadequacy of 5 vegetable oils as substitutes, as well as the characteristics of 22 D-limonene-based substitutes, all less effective in their chemical role, some capable of inducing health problems, and costing more than twice as much as xylene. Some of the 35 alkane-based substitutes discussed are effective for tissue processing, less toxic, with a cost about the same as xylene, but are not very effective for dewaxing and other staining tasks. Isopropanol (2-propanol) alone or mixed with molten paraffin is a technically acceptable and cost-effective substitute for xylene for tissue processing, but in this study, we demonstrate that the best clearing agents from the sectioning quality and diagnostic value point of view, with automated or manual protocols, are mixtures of 5:1 and 2:1 isopropanol and mineral oil, followed by undiluted mineral oil, all at 50 degrees C, making them a safer and cheaper substitute than xylene. Using a 1.7% dishwasher soap aqueous solution at 90 degrees C to dewax before staining and oven drying the stained sections before coverslipping will eliminate xylene from the staining tasks. Tissue processors retorts and conduits can be dewaxed with a 2% solution of a strong glassware laboratory detergent. These 4 methodologies will make the histology laboratory xylene-free but, due to the natural resistance to change, many histotechs will be reluctant to adopt them if they think that their technical expertise could be jeopardized, and the only way these changes will succeed is if the pathologists, as stewards of the histology laboratory, commit to their implementation.