USE OF POLYETHYLENE GLYCOL (PEG, CARBOWAX) AS AN EMBEDDING MEDIUM PRODUCES RESULTS COMPARABLE TO PARAFFIN

Polyethylene glycol (PEG) is a non-carcinogenic, water-soluble polymer of ethylene oxide that has found wide applicability in industry and medicine, and has been used to embed and section small animal and plant tissues. Here we investigate the use of PEG for the rapid embedding of larger plant tissues. Ovaries of Musa velutina, Heliconia psittacorum and eight other species were embedded with a mixture of PEG 1450 and PEG 4000. It was found that tissues up to 6.5 × 10 mm could easily be embedded and sectioned in PEG. Embedded tissues could be stored at room temperature for up to 5 days with no detrimental effects. Sections were easily cut at 8–15 μm on a rotary microtome. PEG embedding resulted in equal or better tissue differentiation, better retention of cell inclusions, and reduced shrinkage compared with paraffin embedding. The process was also faster, requiring only 3–6 h compared with the 2 days needed for paraffin embedding. PEG is a rapid-embedding medium suitable for use with even large plant tissues.

Iodine doping of a photocuring, one-component embedding medium for µCT and histology

Objective: Evaluation of μCT scans of bone implant complexes often shows a specific problem: if an implant material has a very similar radiopacity as the embedding medium (e.g. methacrylate resin), the implant is not visible in the μCT image. Segmentation is not possible, and especially osseointegration as one of the most important parameter for biocompatibility is not evaluable. Methods: To ensure μCT visualisation and contrast enhancement of the evaluated materials, the embedding medium Technovit® VLC7200 was doped with an iodine monomer for higher radiopacity in different concentrations and tested regarding to handling, polymerisation, and histological preparation, and visualisation in µCT. Six different µCT devices were used and compared with regard to scan conditions, contrast, artefacts, image noise, and spatial resolution for the evaluation of the bone-implant blocks. Results: Visualisation and evaluation of all target structures showed very good results in all μCT scans as well as in histology and histological staining, without negative effects caused by iodine doping. Subsequent evaluation of explants of in vivo experiments without losing important information was possible with iodine doped embedding medium. Conclusion: Visualisation of implants with a similar radiopacity as the embedding medium could be considerably improved. µCT scan settings should be selected with the highest possible resolution, and different implant materials should be scanned individually for optimal segmentation. µCT devices with higher resolutions should be preferred. Advances in knowledge: Iodine doped embedding medium is a useful option to increase radiopacity for better visualisation and evaluation of special target structures in µCT.

Oxidation of ultralene and paraffin due to radiation damage after exposure to soft X-rays probed by FTIR microspectroscopy and X-ray fluorescence

Radiation damage upon soft X-ray exposure is an important issue to be considered in soft X-ray microscopy. The work presented here is part of a more extended study on the topic and focuses on the effects of soft X-rays on paraffin, a common embedding medium for soft-tissues, and on ultralene and Si3N4 windows as sample supports. Our studies suggest that the sample environment indeed plays an important role in the radiation damage process and therefore should be carefully taken into account for the analysis and interpretation of new data. The radiation damage effects were followed over time using a combination of Fourier transform infrared (FTIR) microspectroscopy and X-ray fluorescence (XRF), and it was demonstrated that, for higher doses, an oxidation of both embedding medium and ultralene substrate takes place after the irradiated sample is exposed to air. This oxidation is reflected in a clear increase of C=O and O—H infrared bands and on the XRF oxygen maps, correlated with a decrease of the aliphatic infrared signal. The results also show that the oxidation process may affect quantitative evaluation of light element concentrations.

A Rapid Microwave Mediated Polyethyleneglycol Embedding Method Showing Retention of Intracellular Specialized Metabolites in Leaves of Cinnamomum Tamala (Buch-Ham.) T. Nees & Nees

Polyethyleneglycol (PEG) is considered one of the most effective substitutions for paraffin in plant histochemistry as an embedding medium. A rapid and straightforward method of PEG embedding has been developed that resulted in a significant reduction of infiltration time than the traditional method of PEG embedding. The material used for PEG embedding was leaves of Cinnamomum tamala, a member of Lauraceae. Samples were put successively in aqueous solutions of PEG 6000 with increasing concentration for infiltration. A microwave oven was used as a mode of heating medium. The infiltration was completed within 2 h. After the completion of infiltration, the samples were embedded in PEG and solidified. Compared with the existing methods available for PEG infiltration and embedding, this microwave mediated PEG embedding method saves significant time; this also saves the tissue from long-term heat-induced damage. Retention of intracellular metabolites, which was not possible in earlier PEG embedded methods, has also demonstrated in the tissue.

Ultrasound Lumbar Spine Clinical Training Phantom: Which is the Best Embedding Medium?

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Cryo-Gel embedding compound for renal biopsy biobanking

Optimal preservation and biobanking of renal tissue is vital for good diagnostics and subsequent research. Optimal cutting temperature (OCT) compound is a commonly used embedding medium for freezing tissue samples. However, due to interfering polymers in OCT, analysis as mass spectrometry (MS) is difficult. We investigated if the replacement of OCT with Cryo-Gel as embedding compound for renal biopsies would enable proteomics and not disturb other common techniques used in tissue diagnostics and research. For the present study, fresh renal samples were snap-frozen using Cryo-Gel, OCT and without embedding compound and evaluated using different techniques. In addition, tissue samples from normal spleen, skin, liver and colon were analyzed. Cryo-Gel embedded tissues showed good morphological preservation and no interference in immunohistochemical or immunofluorescent investigations. The quality of extracted RNA and DNA was good. The number of proteins identified using MS was similar between Cryo-Gel embedded samples, samples without embedding compound and OCT embedded samples. However, polymers in the OCT disturbed the signal in the MS, while this was not observed in the Cryo-Gel embedded samples. We conclude that embedding of renal biopsies in Cryo-Gel is an excellent and preferable alternative for OCT compound for both diagnostic and research purposes, especially in those cases where proteomic analysis might be necessary.

Fabrication of Atom Probe Tomography Specimens from Nanoparticles Using a Fusible Bi–In–Sn Alloy as an Embedding Medium

We propose a new method for preparing atom probe tomography specimens from nanoparticles using a fusible bismuth–indium–tin alloy as an embedding medium. Iron nanoparticles synthesized by the sodium borohydride reduction method were chosen as a model system. The as-synthesized iron nanoparticles were embedded within the fusible alloy using focused ion beam milling and ion-milled to needle-shaped atom probe specimens under cryogenic conditions. An atom probe analysis revealed boron atoms in a detected iron nanoparticle, indicating that boron from the sodium borohydride reductant was incorporated into the nanoparticle during its synthesis.