Glycol methacrylate embedding in histotechnology: the hematoxylin-eosin stain as a method for assessing the stability of glycol methacrylate sections

ROS Induced by Streptococcus agalactiae Activate Inflammatory Responses via the TNF-α/NF-κB Signaling Pathway in Golden Pompano Trachinotus ovatus (Linnaeus, 1758)

Streptococcus agalactiae is common pathogenic bacteria in aquaculture and can cause mass mortality after fish infection. This study aimed to investigate the effects of S. agalactiae infection on the immune and antioxidant regulatory mechanisms of golden pompano (Trachinotus ovatus). Serum and liver samples were obtained at 0, 6, 12, 24, 48, 96, and 120 h after golden pompano infection with S. agalactiae for enzyme activity and gene expression analyses. After infection with S. agalactiae, the content of reactive oxygen species (ROS) in serum was significantly increased (p < 0.05). Serum levels of glucose (GLU), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and malondialdehyde (MDA) increased and then decreased (p < 0.05), reaching a maximum at 6 h. Serum antioxidant enzyme (LZM) activity increased significantly (p < 0.05) and reached a maximum at 120 h. In addition, the mRNA expression levels of antioxidant genes (SOD, CAT, and GPx) in the liver increased and then decreased, reaching the maximum at 24 h, 48 h, and 24 h, respectively. During the experimental period, the mRNA expression levels of NF-κB-related genes of the inflammatory signaling pathway inhibitory κB (IκB) showed an overall decreasing trend (p < 0.05) and the lowest expression at 120 h, whereas the mRNA expression levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), IκB kinase (IKK), and nuclear factor NF-κB increased significantly (p < 0.05) and the highest expression was at 120 h. In conclusion, these results showed that S. agalactiae could activate internal regulatory signaling in the liver of golden pompano to induce defense and immune responses. This study is expected to lay a foundation to develop the healthy aquaculture of golden pompano and promote a more comprehensive understanding of its disease resistance mechanisms.

Compatibility of staining protocols for bone tissue with Raman imaging

We report the use of Raman microscopy to image mouse calvaria stained with hematoxylin, eosin and toluidine blue. Raman imaging of stained specimens allows for direct correlation of histological and spectral information. A line-focus 785 nm laser imaging system with specialized near-infrared (NIR) microscope objectives and CCD detector were used to collect approximately 100 x 450 micro m Raman images. Principal components analysis, a multivariate analysis technique, was used to determine whether the histological stains cause spectral interference (band shifts or intensity changes) or result in thermal damage to the examined tissue. Image analysis revealed factors for tissue components and the embedding medium, glycol methacrylate, only. Thus, Raman imaging proved to be compatible with histological stains such as hematoxylin, eosin and toluidine blue.

Iso-butanol saturated water: a simple procedure for increasing staining intensity of resin sections for light and electron microscopy

The addition of the alcohol iso-butanol (2-methylpropan-1-ol) to water was found to improve the post-staining procedures for semi-thin and ultrathin resin sections, for both light and electron microscopy. Stain penetration was enhanced with samples embedded in both acrylic and epoxy resins and provided structural information not previously seen. These improvements were found with general (non-specific) stains and a fluorescence stain for light microscopy, as well as for a range of heavy metal stains for electron microscopy. The use of this water/solvent medium also gave improved results when used in a variety of immunogold labelling procedures, resulting in a greater specific label density without affecting background gold levels. The use of this solvent/water medium may have wider applications for other types of staining.

Microencapsulated bovine chromaffin cell xenografts into hemiparkinsonian rats: a drug-induced rotational behavior and histological changes analysis

Bovine chromaffin cells were microencapsulated within alginate-polylysine-alginate (APA) membranes. Microencapsulated bovine chromaffin cells as well as unencapsulated cells and empty microcapsules were grafted into the brain of hemiparkinsonian rats with 6-hydroxydopamine (6-OHDA) lesions. Apomorphine-induced rotational behavior of the host animals and the survival of the grafted chromaffin cells were examined after transplantation. The animals receiving microencapsulated bovine chromaffin cells showed a significant decrease (17.6--35.6%) in apomorphine-induced rotation 1 week postimplantation that remained stable for the 10 month test period. Fluorescent histochemistry further revealed that microencapsulation increased the chromaffin cell survival with only a minimum host reaction for up to 10 months posttransplantation while the survival of free, unencapsulated chromaffin cells was only modest and was accompanied by a large inflammatory response. The reduction of apomorphine-induced rotations was correlated with the survival of bovine chromaffin cells in the host brain. The data indicate that encapsulation of bovine chromaffin cells in APA membranes reduces the host immune response to the xenograft and prolongs the viability of the grafted cells.

Blister artifact formation due to organic solvent effects on Spurr's epoxy resin semithin sections

Wrinkles and air bubble artifacts may occur when preparing slides of semithin sections (0.5 microm) from blocks embedded in different resins. More than aesthetically annoying, wrinkles and air bubble artifacts may prohibit study of small structures. Present observations suggest that organic solvent based mounting media may interact with the resin of the section. This sometimes causes wrinkles and air bubble artifacts in the sections that degrade the quality of light microscope images. We compared the quality of semithin sections of several tissues in different resins using various types of mounting media. We observed that sections from Spurr's resin have many more artifacts. In particular, small, 2-10 microm round or oblong blister-like artifacts often plague our Spurr's resin sections. We demonstrate that Spurr's resin sections react with toluene and xylene in organic solvent based mounting media forming blisters, while sections from Araldite and L. R. White do not. We suggest combinations of embedding and mounting media for successful preparation of semithin sections for light microscopy without wrinkles, blisters, or air bubble artifacts.

Effects of storing initiated 2-hydroxyethyl methacrylate solutions for embedding tissues for light microscopy: some practical implications

The effects of storing 2-hydroxyethyl methacrylate (HEMA) solutions for embedding tissues for light microscopy were studied using three commercially available HEMA embedding kits: Technovit 7100, Technovit 8100, and JB-4. These HEMA solutions were examined at various times of storage over a period of one year using a panel of physicochemical techniques including gas chromatography, titration, viscosimetry, determination of the maximum polymerization temperature and the time required to reach the maximum temperature, and detection of degradation products of HEMA monomers by histochemical procedures. The quality of the resin blocks was examined by the observation of mini-folds in sections. Data obtained from these tests showed that the release of by-products as a result of the degradation of the HEMA monomer during storage of HEMA solutions does not occur. Development of cross-linking agents by transesterification of HEMA monomer was not detected either. Gradual decrease of the inhibitor concentration during storage proved to be the main cause of the reduction of shelf-life of HEMA solutions. Inconsistent tissue infiltration after storage may be due to decreased rates of tissue penetration as a result of HEMA chain lengthening. Guidelines for safe and economical handling of HEMA mixtures are given.

The biological reality of the interlacunar network in the embryonic, cartilaginous, skeleton: a thiazine dye/absolute ethanol/LR White resin protocol for visualizing the network with minimal tissue shrinkage

Third toe phalanges of chicks aged 8-13 days in ovo and 7-day post-natal rat femoral growth plate were examined to determine whether the interlacunar network (IN), a structure with no lipoprotein membrane component or cytoplasmic organelles, is a genuine component of young growth cartilage. In chick phalanges dehydrated by 70% (v/v) ethanol and LR White resin, variable metachromatic staining of the interlacunar network by toluidine blue and red staining by picro-Sirius red indicate the presence of glycosaminoglycans and collagen. The network in phalanges dehydrated by 80% (v/v) ethanol appears little different; however, the network is much less widely detectable in phalanges dehydrated by 90% (v/v) ethanol and, after dehydration by absolute ethanol, is almost completely undetectable. In contrast, when the young cartilage is permeated by a thiazine dye such as toluidine blue, using a solution of dye in the aldehyde fixative, the network is widely detectable, following dehydration by absolute ethanol, both in chick phalanges and in rat growth plate. Comparison of projected areas shows that the extent to which whole chick feet are found to have shrunk, by the time that they are photographed under LR White resin, is determined principally by the extent of dehydration, by 70% (v/v) or absolute ethanol; post-shrinkage areas are 33% or 35% of areas measured in buffer for 70% (v/v) ethanol/LR White resin and 71% or 75% for absolute ethanol/LR White resin (the higher value in each is for the toluidine blue treatment). The network is thus present in radically shrunk tissue, but, significantly, is also fully represented in tissue shrunk by only a conventional margin and is therefore not produced as an artefact by exceptional tissue shrinkage as has been suggested.

Staining sections of water-miscible resins. 2. Effects of staining-reagent lipophilicity on the staining of glycol-methacrylate-embedded tissues

Glycol methacrylate (GMA) sections of animal tissues were stained with a group of twenty-seven reagents of very varied chemical characteristics. The artefactual background staining of the resin was found to be dependent on the hydrophilic/lipophilic character of the staining reagent, as estimated from the logarithm of its octanol-water partition coefficient (log P). Intense background staining occurred with lipophilic stains, whose log P greater than 2. In keeping with this, use of GMA semi-permeable membranes for enzyme histochemistry failed to give staining when using a lipophilic substrate, probably because the substrate was trapped in the membrane. An analysis of other routine histochemical stains--in terms of the probable occurrence of high resin background staining and low tissue sensitivity--is made. A numerical guide is provided to help avoid artefacts resulting from hydrophobic and size effects. Note: small, hydrophilic reagents (log P less than 0; molecular weight less than 550 Da) are least likely to show either type of artefact. Conversely, reagents which are lipophilic, or/and of intermediate size (log P greater than 2; 550 less than ionic weight less than 1000 Da), give strong background staining.

A numerical procedure for choosing effective, low toxicity plasticizers for glycol methacrylate embedding

A numerical method for selecting low toxicity plasticizers for glycol methacrylate (GMA) embedding mixtures is described. It involves use of various numerical parameters, namely; molecular weight, melting point, solubility parameter, and toxicity data. On the basis of these parameters, nine plasticizers were selected. Their effects on microtomy and tissue processing, and also their influence on tissue morphology and staining, were investigated. For tissue processed at low temperatures into GMA, using ethanol dehydration, the following compounds were as satisfactory as 2-butoxyethanol whilst being less toxic: 2-isopropoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-(n-butoxyethoxy)ethanol. However for tissues processed using the plasticizer as dehydrating agent, the optimum plasticizers were 2-isopropoxyethanol, 2-(2-methoxyethoxy)ethanol and 2-(2-ethoxyethoxy)ethanol. It is possible to give a numerical specification of the preferred plasticizers, and for the first procedure this is: a solubility parameter in the range 21-26 J0.5 cm-1.5 or higher, a melting point well below 0 degree C, and a rat oral LD50 greater than 12.52 mmol kg-1. It was also possible to analyse the differential effects of the dehydrating agents on histochemical and enzyme histochemical staining on a numerical basis, using a structure-activity relations approach.

Modified hematoxylin and eosin staining method for epoxy-embedded tissue sections

A modified hematoxylin and eosin staining method for glutaraldehyde fixed, osmium tetroxide postfixed, and epoxy resin (Medcast Resin) embedded tissue is described. Two microns thick sections of human and animal tissues are treated with 4% H2O2 for 4 minutes, washed, dryed, and then flooded with Gill's III hematoxylin in a moist chamber at 37 degrees C for 90 minutes. Subsequent steps are: washing; bluing in ammonia water for 1 minutes; washing again and staining in 1% eosin Y alcoholic solution for 5 minutes; rinsing in 100% ethanol; drying and mounting with Permont. This procedure is quick, easy and successful in demonstrating both color scale and quality similar to hematoxylin and eosin stains obtained in standard paraffin sections.

Sudan black B as a histological stain for polymeric biomaterials embedded in glycol methacrylate

Sudan black B, usually a stain for all kinds of lipid, turned out to be an excellent histological stain for polymeric biomaterials embedded in glycol methacrylate. Staining the surrounding connective tissue with toluidine blue-basic fuchsin makes details of the polymer-tissue interface clearly visible. Sudan black B might be used to visualize the biodegradation process of polymeric biomaterials.