The morphology of organelles, some of their functions and their relationships to one another have been derived from ultrastructural studies 11, 12, 13. It has provided an understanding of the structure and organization of the components of tissue, cells and organisms. TEM continues to play a critical role in discovering and describing new organisms, especially viruses, and rendering viral diagnosis in, for example, diarrheal diseases. Once the image is finally focused with the magnetic lenses, the film is exposed or the image is captured with a digital camera. The differential transmission of the electrons creates an image that is captured on a fluorescent screen, where it is viewed through a binocular microscope. ![]() The electron beam passes through an ultrathin plastic section whose tissue and cellular components have been post-fixed in osmium and impregnated with the heavy metals uranyl and lead, which impede the beam in proportion to their respective degrees of electron density. The transmission electron microscope employs a fine electron beam, created by a high-voltage, electric current-heated tungsten filament, focused by magnetic lenses. Papers appeared describing progressively better techniques for specimen processing, as the transmission electron microscope became easier to use and more widely available. Details of fixation, embedding and how to prepare thin and semi-thin sections, which can be used for analysis complementary to that performed ultimately using TEM, are also described.Ĭommencing circa 1950, the development of the transmission electron microscope revolutionized microscopy, progressively bringing it to new levels of magnification and resolution 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. In this protocol, we present a TEM method for preparing specimens obtained in clinical or research settings, discussing the particular requirements for tissue and cell preparation and analysis, the need for rapid fixation and the possibility of analysis of tissue already fixed in formalin or processed into paraffin blocks. ![]() TEM is used to study the morphology of cells and their organelles, and in the identification and characterization of viruses, bacteria, protozoa and fungi. Ultrastructural examination of tissues, cells and microorganisms plays a vital role in diagnostic pathology and biologic research. TEM enables the resolution and visualization of detail not apparent via light microscopy, even when combined with immunohistochemical analysis. In transmission electron microscopy (TEM), electrons are transmitted through a plastic-embedded specimen, and an image is formed.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |