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Keene DR, Tufa SF. Connective Tissue Ultrastructure: A Direct Comparison between Conventional Specimen Preparation and High-Pressure Freezing/Freeze-Substitution. Anat Rec (Hoboken) 2019; 303:1514-1526. [PMID: 31251834 DOI: 10.1002/ar.24211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/28/2018] [Accepted: 01/18/2019] [Indexed: 11/11/2022]
Abstract
It is generally agreed within the microscopy community that the quality of ultrastructure within the connective tissue matrix resulting from high-pressure freezing followed by freeze-substitution (HPF/FS) far exceeds that gained following the "conventional" preparation method, which includes aqueous fixation, dehydration, and embedding. Exposure to cryogen at high pressure is the only cryopreservation method capable of vitrifying tissue structure to a depth exceeding 200 μm. Cells within connective tissues prepared by HPF/FS are universally larger, filling the commonly seen void at the juncture between cell and matrix. Without significant shrinkage of cells and the coincident extraction of the cytosolic components, well-resolved organelles are less clustered within an expanded cytosol. Much of the artifact from "conventional" methods occurs as large space filling and also smaller fibril-associated proteoglycans are extracted during fixation. However, the visualization of some matrix features by electron microscopy is actually dependent on the collapse or extraction of these "masking" components. Herein, we argue that an impression of ultrastructure within commonly studied matrices, in particular skin, is best gained following the evaluation of both conventional preparations and tissue prepared by HPF/FS. Anat Rec, 2019. © 2019 American Association for Anatomy.
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Affiliation(s)
- Douglas R Keene
- Shriners Hospital for Children Micro-Imaging Center, Portland, Oregon.,Department of Biomechanical Engineering, Oregon Health Sciences University, Portland, Oregon.,Department of Medical Genetics, Oregon Health Sciences University, Portland, Oregon
| | - Sara F Tufa
- Shriners Hospital for Children Micro-Imaging Center, Portland, Oregon
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2
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Molecular architecture and function of the hemidesmosome. Cell Tissue Res 2015; 360:529-44. [PMID: 26017636 PMCID: PMC4452579 DOI: 10.1007/s00441-015-2216-6] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 11/03/2014] [Indexed: 01/13/2023]
Abstract
Hemidesmosomes are multiprotein complexes that facilitate the stable adhesion of basal epithelial cells to the underlying basement membrane. The mechanical stability of hemidesmosomes relies on multiple interactions of a few protein components that form a membrane-embedded tightly-ordered complex. The core of this complex is provided by integrin α6β4 and P1a, an isoform of the cytoskeletal linker protein plectin that is specifically associated with hemidesmosomes. Integrin α6β4 binds to the extracellular matrix protein laminin-332, whereas P1a forms a bridge to the cytoplasmic keratin intermediate filament network. Other important components are BPAG1e, the epithelial isoform of bullous pemphigoid antigen 1, BPAG2, a collagen-type transmembrane protein and CD151. Inherited or acquired diseases in which essential components of the hemidesmosome are missing or structurally altered result in tissue fragility and blistering. Modulation of hemidesmosome function is of crucial importance for a variety of biological processes, such as terminal differentiation of basal keratinocytes and keratinocyte migration during wound healing and carcinoma invasion. Here, we review the molecular characteristics of the proteins that make up the hemidesmosome core structure and summarize the current knowledge about how their assembly and turnover are regulated by transcriptional and post-translational mechanisms.
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Molecular architecture and function of the hemidesmosome. Cell Tissue Res 2014; 360:363-78. [PMID: 25487405 PMCID: PMC4544487 DOI: 10.1007/s00441-014-2061-z] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 11/03/2014] [Indexed: 01/07/2023]
Abstract
Hemidesmosomes are multiprotein complexes that facilitate the stable adhesion of basal epithelial cells to the underlying basement membrane. The mechanical stability of hemidesmosomes relies on multiple interactions of a few protein components that form a membrane-embedded tightly-ordered complex. The core of this complex is provided by integrin α6β4 and P1a, an isoform of the cytoskeletal linker protein plectin that is specifically associated with hemidesmosomes. Integrin α6β4 binds to the extracellular matrix protein laminin-332, whereas P1a forms a bridge to the cytoplasmic keratin intermediate filament network. Other important components are BPAG1e, the epithelial isoform of bullous pemphigoid antigen 1, BPAG2, a collagen-type transmembrane protein and CD151. Inherited or acquired diseases in which essential components of the hemidesmosome are missing or structurally altered result in tissue fragility and blistering. Modulation of hemidesmosome function is of crucial importance for a variety of biological processes, such as terminal differentiation of basal keratinocytes and keratinocyte migration during wound healing and carcinoma invasion. Here, we review the molecular characteristics of the proteins that make up the hemidesmosome core structure and summarize the current knowledge about how their assembly and turnover are regulated by transcriptional and post-translational mechanisms.
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Butler MK, Prow TW, Guo YN, Lin LL, Webb RI, Martin DJ. High-pressure freezing/freeze substitution and transmission electron microscopy for characterization of metal oxide nanoparticles within sunscreens. Nanomedicine (Lond) 2012; 7:541-51. [DOI: 10.2217/nnm.11.149] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Aims: To date, the description of a single, suitable method to observe in detail metal oxide nanoparticles in situ within sunscreens is currently lacking, despite growing concern as to how they interact with humans. This study explores the usefulness of transmission electron microscopy to characterize the nanoparticles in sunscreens. Materials & methods: High-pressure freezing then freeze substitution was used to prepare resin-embedded commercial sunscreen samples, and ultrathin sections of these were observed with transmission electron microscopy. Conventional room temperature processing for resin embedding was also trialed. Results: High-pressure frozen/freeze substituted samples provided clear visualization of the size and shape of the nanoparticles and agglomerates and allowed further characterization of the composition and crystal form of the metal oxides, while conventionally processed chemically fixed samples were subject to distribution/agglomeration artifacts. Conclusion: Transmission electron microscopy of high-pressure frozen/freeze substituted samples is an ideal method to completely observe metal oxide nanoparticles in situ in sunscreens.
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Affiliation(s)
- Margaret K Butler
- Australian Microscopy & Microanalysis Research Facility & Australian Institute for Bioengineering & Nanotechnology, Cnr College & Cooper Roads, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Tarl W Prow
- Therapeutics Research Centre & Dermatology Research Centre, School of Medicine, The University of Queensland, Level 2 Building 33, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Queensland, 4102, Australia
| | - Ya-Nan Guo
- Centre for Microscopy & Microanalysis & School of Engineering, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Lynlee L Lin
- Therapeutics Research Centre & Dermatology Research Centre, School of Medicine, The University of Queensland, Level 2 Building 33, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Queensland, 4102, Australia
| | - Richard I Webb
- Centre for Microscopy & Microanalysis, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Darren J Martin
- Australian Institute for Bioengineering and Nanotechnology, Cnr College & Cooper Roads, The University of Queensland, Brisbane, Queensland, 4072, Australia
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Strádalová V, Gaplovská-Kyselá K, Hozák P. Ultrastructural and nuclear antigen preservation after high-pressure freezing/freeze-substitution and low-temperature LR White embedding of HeLa cells. Histochem Cell Biol 2008; 130:1047-52. [PMID: 18797913 DOI: 10.1007/s00418-008-0504-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2008] [Indexed: 12/01/2022]
Abstract
A protocol for high-pressure freezing and LR White embedding of mammalian cells suitable for fine ultrastructural studies in combination with immunogold labelling is presented. HeLa S3 cells enclosed in low-temperature gelling agarose were high-pressure frozen, freeze-substituted in acetone, and embedded in LR White at 0 degrees C. The morphology of such cells and the preservation of nuclear antigens were excellent in comparison with chemically fixed cells embedded in the same resin. The immunolabelling signal for different nuclear antigens was 4-to-13 times higher in high-pressure frozen than in chemically fixed cells. We conclude that one can successfully use high-pressure freezing/freeze-substitution and LR White embedding as an alternative of Lowicryl resins.
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Affiliation(s)
- Vendula Strádalová
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, v.v.i., Vídenská 1083, 142 20, Prague, Czech Republic
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Reipert S, Wiche G. Chapter 10 High-Pressure Freezing and Low-Temperature Fixation of Cell Monolayers Grown on Sapphire Coverslips. Methods Cell Biol 2008; 88:165-80. [DOI: 10.1016/s0091-679x(08)00410-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Sosinsky GE, Crum J, Jones YZ, Lanman J, Smarr B, Terada M, Martone ME, Deerinck TJ, Johnson JE, Ellisman MH. The combination of chemical fixation procedures with high pressure freezing and freeze substitution preserves highly labile tissue ultrastructure for electron tomography applications. J Struct Biol 2007; 161:359-71. [PMID: 17962040 DOI: 10.1016/j.jsb.2007.09.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 09/05/2007] [Accepted: 09/06/2007] [Indexed: 10/22/2022]
Abstract
The emergence of electron tomography as a tool for three dimensional structure determination of cells and tissues has brought its own challenges for the preparation of thick sections. High pressure freezing in combination with freeze substitution provides the best method for obtaining the largest volume of well-preserved tissue. However, for deeply embedded, heterogeneous, labile tissues needing careful dissection, such as brain, the damage due to anoxia and excision before cryofixation is significant. We previously demonstrated that chemical fixation prior to high pressure freezing preserves fragile tissues and produces superior tomographic reconstructions compared to equivalent tissue preserved by chemical fixation alone. Here, we provide further characterization of the technique, comparing the ultrastructure of Flock House Virus infected DL1 insect cells that were (1) high pressure frozen without fixation, (2) high pressure frozen following fixation, and (3) conventionally prepared with aldehyde fixatives. Aldehyde fixation prior to freezing produces ultrastructural preservation superior to that obtained through chemical fixation alone that is close to that obtained when cells are fast frozen without fixation. We demonstrate using a variety of nervous system tissues, including neurons that were injected with a fluorescent dye and then photooxidized, that this technique provides excellent preservation compared to chemical fixation alone and can be extended to selectively stained material where cryofixation is impractical.
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Affiliation(s)
- Gina E Sosinsky
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California, San Diego, 1070 Basic Science Building MC 0608, 9500 Gilman Drive, La Jolla, CA 92093-0608, USA.
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Matsuura S, Koyama N, Kashimata M, Hayashi H, Kikuta A. Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland. Anat Sci Int 2007; 82:164-74. [PMID: 17867343 DOI: 10.1111/j.1447-073x.2007.00182.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland was examined under light microscopic histochemistry and electron microscopy. To avoid loss of water-soluble glycogen during histological tissue preparation, fixation with ethanol and embedding in hydrophilic glycol methacrylate resin was used for light microscopy, and high-pressure freezing/freeze substitution for electron microscopy. Glycogen was detected on periodic acid-Schiff stain, periodic acid-thiosemicarbazide-silver proteinate reaction, and the digestion test with alpha-amylase. On embryonic day 14, glycogen began to accumulate in the proximal portions of the developing epithelial cords. On embryonic day 17, marked glycogen particles were seen at the basal portion of the ductal epithelial cells and an abrupt increase of glycogen accumulation occurred in the secretory cells in the terminal bulbs. Ultrastructural observation indicated large clumps of glycogen particles localized in the basal portion of the terminal bulb cells. The initiation of glycogen accumulation preceded the formation of lumens in the ducts and terminal bulbs. Furthermore, proliferation analysis by bromodeoxyuridine labeling showed that this glycogen accumulation followed the cessation of the epithelial cell proliferation. Postnatally, glycogen accumulation in the terminal bulbs became gradually inconspicuous and completely disappeared by postnatal day 3, but that in the ducts was retained until around postnatal day 12. Temporary glycogen accumulation after the cell proliferation and before/during the lumen formation and secretory granule formation suggests significant involvement of the carbohydrate metabolism in the organogenesis of the submandibular gland.
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Affiliation(s)
- Sachiko Matsuura
- Department of Oral Histology, Matsumoto Dental University, Shiojiri, Japan.
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Affiliation(s)
- Kent McDonald
- Electron Microscope Laboratory, University of California, Berkeley, California 94720, USA
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Müller-Reichert T, Srayko M, Hyman A, O'Toole ET, McDonald K. Correlative light and electron microscopy of early Caenorhabditis elegans embryos in mitosis. Methods Cell Biol 2007; 79:101-19. [PMID: 17327153 DOI: 10.1016/s0091-679x(06)79004-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Thomas Müller-Reichert
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), 01307 Dresden, Germany
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Mulholland WJ, Arbuthnott EAH, Bellhouse BJ, Cornhill JF, Austyn JM, Kendall MAF, Cui Z, Tirlapur UK. Multiphoton high-resolution 3D imaging of Langerhans cells and keratinocytes in the mouse skin model adopted for epidermal powdered immunization. J Invest Dermatol 2006; 126:1541-8. [PMID: 16645596 DOI: 10.1038/sj.jid.5700290] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Langerhans cells (LCs) can be targeted with DNA-coated gold micro-projectiles ("Gene Gun") to induce potent cellular and humoral immune responses. It is likely that the relative volumetric distribution of LCs and keratinocytes within the epidermis impacts on the efficacy of Gene Gun immunization protocols. This study quantified the three-dimensional (3D) distribution of LCs and keratinocytes in the mouse skin model with a near-infrared multiphoton laser-scanning microscope (NIR-MPLSM). Stratum corneum (SC) and viable epidermal thickness measured with MPLSM was found in close agreement with conventional histology. LCs were located in the vertical plane at a mean depth of 14.9 microm, less than 3 mum above the dermo-epidermal boundary and with a normal histogram distribution. This likely corresponds to the fact that LCs reside in the suprabasal layer (stratum germinativum). The nuclear volume of keratinocytes was found to be approximately 1.4 times larger than that of resident LCs (88.6 microm3). Importantly, the ratio of LCs to keratinocytes in mouse ear skin (1:15) is more than three times higher than that reported for human breast skin (1:53). Accordingly, cross-presentation may be more significant in clinical Gene Gun applications than in pre-clinical mouse studies. These interspecies differences should be considered in pre-clinical trials using mouse models.
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Affiliation(s)
- William J Mulholland
- Department of Engineering Science, Oxford Institute of Biomedical Engineering, University of Oxford, Oxford, UK
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Spazierer D, Fuchs P, Reipert S, Fischer I, Schmuth M, Lassmann H, Wiche G. Epiplakin is dispensable for skin barrier function and for integrity of keratin network cytoarchitecture in simple and stratified epithelia. Mol Cell Biol 2006; 26:559-68. [PMID: 16382147 PMCID: PMC1346901 DOI: 10.1128/mcb.26.2.559-568.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epiplakin, a giant epithelial protein of >700 kDa, belongs to the plakin family of cytolinker proteins. It represents an atypical family member, however, as it consists entirely of plakin repeat domains but lacks any of the other domains commonly shared by plakins. Hence, its putative function as a cytolinker protein remains to be shown. To investigate epiplakin's biological role, we generated epiplakin-deficient mice by gene targeting in embryonic stem cells. Epiplakin-deficient mice were viable and fertile, without developing any discernible phenotype. Ultrastructurally, their epidermis revealed no differences compared to wild-type littermates, and cornified envelopes isolated from skin showed no alterations in shape or stability. Furthermore, neither embryonal formation nor later function of the epithelial barrier was affected. In primary cultures of epiplakin-deficient keratinocytes, the organization of actin filaments, microtubules, and keratin networks was found to be normal. Similarly, no alterations in keratin network organization were observed in simple epithelia of small intestine and liver or in primary hepatocytes. We conclude that, despite epiplakin's abundant and highly specific expression in stratified and simple epithelia, its absence in mice does not lead to severe skin dysfunctions, nor has it detectable consequences for keratin filament organization and cytoarchitecture of cells.
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Affiliation(s)
- Daniel Spazierer
- Department of Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
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Gerbersdorf SU. An advanced technique for immuno-labelling of microcystins in cryosectioned cells of Microcystis aeruginosa PCC 7806 (cyanobacteria): Implementations of an experiment with varying light scenarios and culture densities. Toxicon 2006; 47:218-28. [PMID: 16376961 DOI: 10.1016/j.toxicon.2005.10.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 10/28/2005] [Accepted: 10/31/2005] [Indexed: 10/25/2022]
Abstract
The intracellular localisation of cyanobacterial toxins might well indicate production sites and possible shifts to destination points, thus giving information on possible functions of these toxins within algal cells or at the ecological level beyond. By preparing cells of Microcystis aeruginosa PCC 7806 by cryofixation/cryosectioning and using purified high quality antibodies for immunogold-localisation, excellent ultrastructural integrity and labelling of microcystins was shown. Compared to conventional techniques, including organic solvents, possible dislocation/extraction was significantly minimised, hence, the labelling density was enhanced and the labelling pattern changed. The microcystins were mainly localised within the inner nucleoplasmic area and accumulations of epitopes could be detected around/within intracellular inclusions, such as polyphosphate bodies and carboxysomes. Photosynthetic active radiation (PAR) had a significant effect on microcystin biosynthesis, and the medium light intensity of 25 microE m(-2) s(-1) induced the highest intracellular microcystin contents (up to 160 epitopes per cell and 26 epitopes per microm2). The restriction of the full light spectrum to blue (400-500 nm) or red (>610 nm) wavelengths did not result in any significant effect on microcystin production. However, the subcultures harvested at higher optical densities (>0.5) revealed significantly higher microcystin labelling compared to the less dense cell cultures (OD < 0.5). Altogether, the possibility was discussed whether microcystin might function as an inhibitor of RUBISCO under conditions of C-limitations. The effects of light intensity and cell suspension density on intracellular microcystin shown by immuno-detection matched the pattern of microcystin concentrations determined in parallel by HPLC and ELISA.
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Affiliation(s)
- Sabine Ulrike Gerbersdorf
- Hydraulic Laboratory, Institute of Hydraulic Engineering, University of Stuttgart, Pfaffenwaldring 61, 70550 Stuttgart, Germany.
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van der Wel NN, Fluitsma DM, Dascher CC, Brenner MB, Peters PJ. Subcellular localization of mycobacteria in tissues and detection of lipid antigens in organelles using cryo-techniques for light and electron microscopy. Curr Opin Microbiol 2005; 8:323-30. [PMID: 15939357 DOI: 10.1016/j.mib.2005.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
The survival of intracellular pathogens within a host is determined by microbial evasion, which can be partially attributed to their subcellular trafficking strategies. Microscopic techniques have become increasingly important in understanding the cell biology of microbial infections. These recently developed techniques can be used for the subcellular localization of antigens not only in cultured cells but also within tissues such as Mycobacterium tuberculosis in lung and Mycobacterium leprae in skin. High-resolution immunofluorescence microscopy can be used in combination with cryo-immunogold electron microscopy using consecutive cryo-sections on the same tissue block forming a direct connection between the two microscopy techniques. The detection of mycobacterial lipid antigens in situ at an ultrastructural level is currently a challenge, but new modifications can be used to address this. These methods might be of interest to microbiologists and cell biologists who study host-pathogen interactions.
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Affiliation(s)
- Nicole N van der Wel
- The Netherlands Cancer Institute, Plesmanlaan 121 - H4, 1066 CX Amsterdam, The Netherlands
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