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Practical 2

Practical 2. Types of structures seen in light microscope.

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Practical 2

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  1. Practical 2

  2. Types of structures seen in light microscope Branche filaments, spirals, vibrio, thic rod, tetraede – 4 cocci, staphylococci– grapes of cocci, streptococci – chain of cocci, diplococci – double of cocci ( lancets shape – flame and candle, coffee beans), different spirals. Leptospira interrogans ?

  3. Microscope - light Enlargement: 2 systems of lenses to make the picture enlarge – ocular lenses nad objective lenses Objective lenses: –power x10: general overview – x 40: big microbes (parasites and their cysts and eggs, filamentous fungi) – x 100 with immersion oil : bacteria, yeast, morphological details Ocular lenses: usually x 10, x 25 The power of microscope equals the multiplication of the objective and occcular lenses power Discirmination properties: are given by the wave lenghth of the light beam and by the angle in wich the light beam enters the lens of the objective – numeric aperture: 2 /um –

  4. Light microscope Index of light of the background and of the bacteriu, is almost the same = the discrimination is bad – native smear – living bacteria (movement, budding - stained, colored smears (the contrast between microbe and bacgound is greate) – better discrimination + identification of some subceluluar structures Darkfield microscopy – the sample is visualised by the light beam entering from the perifery – large angle (0,1/um – 0,2/um) – Treponema, Borrelia, Leptospira Microscopy with interference – filtration system visualise the phase differences of the light beam after its passing through objects with different density The system anable 3 dimensional picture

  5. SMEARS

  6. Improoving the discrimination properties of light microscope Vibrio, rod with spores, sprial filamentous rods, spirochets, staphylococci, streptobacili – rods in chain, streptococci, tetrades, diplococci

  7. Negative staining amelioration of the contrast against the dark background- Burri method – capsule is uncolored, - Gram staining – negative staining of staphylococci or spores that are not stained

  8. Fluorescein microscope Mercury vacuum lamp emits the light of shorter wavelenght The smear is prepared with fluorochromes – compositions that can absorbe the short lenght´s ultraviolet or ultrablue light and can emit energy of higher wavelenght Fluorochromes that stain the smear – fluorescence staining – that after the beam touch it will emit the green fluorescein light Highly sensitive

  9. Electron microscop Uses the magnet – not lenses – to direct the beam of electrons throught speciment to the screen. This process uses the shorter wavelenghts of light.Higher discrimination Visualisation of viruses and subcellular structures 2 types – transmission – beams enter directly throught the sample – scanning – beams enter the sample in the angle 3 dimmensional picture

  10. Possibilities in visualisation of bacterial sporesnegative staining, WirtzConcklin, transmission electron microscopy, scanning electron microscopy

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