Histology 1

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  1. Brightfield microscopy
    viewing a thin transilluminated specimen; use of dyes and thin sections
  2. Polarization microscopy
    specimen placed between two polarizing filters, light striking oriented molecules is rotated and contrasted against background
  3. Birefringence
    the ability to rotate polarized light; necessary for polarization microscopy
  4. Fluorescence Microscopy
    specimen stained with a fluorescent dye and irradiated with UV light
  5. Dark Field Microscopy
    light rays directed towards the specimen at an angle. Reflected rays pass through the ocular, illuminate specimen; rarely used - primarily used when testing for syphillis
  6. Phase Contrast Microscopy
    No dyes used, specimen are essentially transparent. Dependent upon light changing speed as it passes through media with different refractive indices; used for observing living cells
  7. Differential Interverence Contrast Microscopy
    similar to phase contrast, but emplys additional prisms and polarizers to generate contrast; useful for visualizing the surface of living cells
  8. Image Processing
    a microscope is linked to a computer and monitor, which is used to measure certain cellular features
  9. Fixation
    First step in tissue processing; immersing the tissue in a fixative that permeates the specimen and cross-links macromolecules together. Typically formalin is used, but can also be performed by picric acid, osmium tetroxide, and gluteraldehyde. Tissue shrinkage typically occurs
  10. Decalcification
    Second (optional) step of tissue processing. Hard tissue is immersed in an acid solution (typically formic, hydrochloric or nitric acid) to remove calcium salts, softening it an enabling sectioning; usually performed on bone / teeth to make sectioning simpler
  11. Dehydration
    Third step of tissue processing. Progressive bathing of sample in more and more concentrated alcohol, removing water from the specimen
  12. Clearing
    Fourth step of tissue processing. Alcohol from dehydration is replaced by a solvent, typically xylene, rendering the tissue transparent, then tissue is infused with melted paraffin
  13. Embedding
    Fifth step of tissue processing. Tissue is encased in paraffin (light microscopy) or plastic resins (ultrathin sectioning or EM) in order to stabilize it when sectioning
  14. Sectioning
    Sixth step of tissue processing. Typically carried out using a microtome or a cryostat
  15. Rehydration
    Seventh step of tissue processing. Performed prior to staining so the tissue can absorb the stain. Xylene is introduced to dissolve the paraffin, which is then replaced by progressively more dilute alcohol concentrations until only water remains
  16. Staining
    Infusing colored stains into tissue sections to make identification of cellular structures easier
  17. Basophilia
    "base lover" - tissue stains more readily with basic dyes. Typically acidic material (DNA, RNA)
  18. Acidophilia
    "acid lover" - tissue stains more readily with acid dyes. Typically basic material (proteins and cytoplasmic components)

    "eosinophilic" is often used in place of "acidophilic" because eosin readily stains basic materials
  19. Metachromasia
    change in dye color when reacting to certain tissue constituents; typically seen when concentrated basic dyes are used. Large molecular aggregates form that transmit light differently than is seen with dispersed dye molecules.
  20. Identify this (these) stain(s)
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    Hematoxylin & Eosin

    blue - hematoxylin, binds nucleus, acidic regions of cytoplasm and cartilage matrix

    pink - eosin, binds basic cytoplasmic regions, collagen, proteinaceous areas
  21. Identify this stain
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    Sudan black

    stains lipids black
  22. Identify this stain
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    Periodic acid-Schiff (PAS)

    neutral carbohydrates and glycoproteins stain magenta; typically used to demonstrate glycogen, basement membrane material, and mucus. Considered a carbohydrate stain
  23. Identify this stain
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    Alcian blue

    acidic carbohydrates (glycosaminoglycans) stain blue. Considered a carbohydrate stain
  24. Identify this stain
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    fine structures, such as nerve processes and reticular fibers (stains black)
  25. Identify this stain
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    stains lipid-containing structures black
  26. Identify this stain
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    Trichrome (Mallory, Masson's)

    • dark blue - nuclei
    • red - keratin, muscle, cytoplasm
    • light blue - collagen
  27. Counterstain
    stains applied to increase contrast of previously stained structures (i.e. background staining)
  28. This image is an example of:
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    Histochemistry - definition cut off in lecture manual

    • Textbook definition:
    • Methods for localizing substances in tissue sections by utilizing specific chemical reactions. Meant to form insoluble complexes with the purpose of identifying specific structures within a cell
  29. This picture is an example of:
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    Immunohistochemistry (immunocytochemistry)

    individual molecules are localized via antibodies to those molecules, and enzymes are linked to those antibodies to be stained.

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  30. Transmission Electron Microscopy
    focuses electrons from a heated metallic filament onto a specimen, up to 1000x resolution of light microscopy (between 1/3-3nm resolution). Tissue sections must be very thin. Fixation via gluteraldehyde, osmium tetroxide, paraformaldehyde and potassium permanganate.

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  31. Scanning Electron Microscopy
    generates a 3D image of the surface of a specimen. Requires a thin film of heavy metal atoms to be applied to the specimen. Electron beam is focused over the surface sequentially, reflecting into a detector which generates the image and displays it on a monitor

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  32. Fertilization
    Joining of sperm and oocyte, typically within the fallopian tube, inducing the second meiotic division in the oocyte. Acrysomal cap of the sperm contains enzymes allowing it to breach the corona radiata and pierce through the zona pellucida into the oocyte

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  33. Morula
    mass of 12 blastomeres (small cells resultant from rapid divisions following fertilization); appears ~3 days after fertilization

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  34. Blastocyst
    Structure developed from the Morula, composed of embryoblast (large mass of cells), blastocystic cavity, and trophoblast (cells surrounding the cavity)

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  35. Syncitiotrophoblast, Cytotrophoblast
    Differentiated elements of the trophoblast following attachment to the uterine wall

    Syncytiotrophoblast - incorporates itself into the uterine wall

    Cytotrophoblast - lining of the blastocyst

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  36. Bilaminar embryonic disc
    forms during week 2 post-fertilization. Resulting from embryoblastic cavity forming (eventually the amniotic cavity), generating columnar cells lining up against the hypoblast (referred to as epiblastic cells)
  37. Hypoblast & Epiblast
    Hypoblast - cells lining the surface of the embryoblast, 1/2 of the bilaminar cavity

    Epiblast - columnar cells against the hypoblast, adjacent to the amniotic cavity

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  38. Lacunar spaces
    develop within the syncytiotrophoblast and fill with maternal blood to supply early embryo with nutrion via diffusion
  39. Primary Chorionic Villi
    fingerlike extensions of the cytotrophoblast into the syncytiotrophoblast - develops 2 days after the development of lacunar spaces
  40. Prechordal Plate
    columnar development of hypoblast cells, forming a thickened circular structure in the bilaminar disc at ~14 days post-fertilization
  41. Gastrulation
    during the 3rd week of development, the point at which the three germ layers form, resulting in a trilaminar embryonic disc. Signals the start of morphogenesis (development of the body form)
  42. Primitive Streak
    beginning of gastrulation process. Results from epiblast cells proliferating and migrating between the two layers of the bilaminar disc. Eventually regresses by the end of the 4th developmental week, embryo remains bilaminar at the future sites of the mouth and anus

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  43. Primitive Node
    the thickening of the primitive streak at the cranial end
  44. Primitive Groove
    the lengthening of the primitive streak
  45. Primitive Pit
    the end result of the primitive node and primitive groove lengthing and widening the primitve streak

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  46. Mesenchyme
    resulting tissue from the epiblast cell migration between the two lamellae. Some mesenchyme will become embryonic mesoderm, some will migrate to replace the hypoblast, forming embryonic endoderm
  47. Epiblast Derivatives
    the epiblast gives rise to three new germ layers through gastrulation, including ectoderm, mesoderm and endoderm
  48. Ectoderm Derivatives
    Epidermis / epidermal appendages, the nervous system, eye and inner ear, connective tissue of the head, and the neural crest
  49. Neural Crest
    peaks of the neural plate; pinch the neural folds together to form the neural tube

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  50. Mesoderm Derivatives
    skeletal muscle, blood cells, epithelium of blood vessels, visceral smooth muscle, mesothelium (lining of body cavity), reproductive and urinary organs / ureters, most of the cardiovascular system, connective tissue, bones and ligaments of the trunk
  51. Endoderm Derivatives
    thyroid and parathyroid glands, epithelial linings of the respiratory and gastrointestinal tracts + their glandular components, and that of the inner ear
  52. Neurulation
    Process resulting in the formation of the neural tube; induced by the development of the notochord
  53. Notochord functions
    • 1. induce neurulation
    • 2. define the long axis of the embryo
    • 3. rigidify the embryo
    • 4. signal certain cells to develop into axial muscles and bones, as well as elements of the NCS
    • 5. form parts of the intervertebral discs
  54. Neural Plate
    thickening of cells overlying the notochord. Eventually gives rise to CNS and retinas

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Card Set:
Histology 1
2013-09-09 03:13:26

Atlas / Textbook images of tissues discussed in class. Dedicated primarily to Dr. Rinaggio's lectures to incorporate images from the atlas with the lecture manual. updated 9/8/2013 - lecture 1, part 1 of lecture 2 included. Images may be included more than once, if they contain references to multiple terms used
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