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25 Cards in this Set

  • Front
  • Back

Coulter principle

  • passage of each cell through the aperture creates an electrical pulse which appears as a spike on the oscilloscope screen
  • The height of each spike is proportional to the size of the cell.

Threshold and channels

  • To choose a pulse size we use an electronically set size limit called a Threshold.
  • We can use a series of thresholds to sort cells of a population into many subgroups by size. The area between thresholds is a Channel

Aperture Impedance

System uses Sweep Flow

  • Eliminates recirculation of cells
  • Cells pushed away from critical (counting) zone by diluent
  • More accurate counts

Normal RBC histogram

  • Most RBCs fall between 80 and 100 fl.
  • histogram should start at the baseline on the left and a small “tail” may be evident on the right = doublets and triplets (cells that go through the aperture in twos and threes).
  • These are excluded from the RBC MCV by algorithms but may be seen on the histogram.

normal RBC

Normal platelet histogram

abnormal platelets - large platelets

abnormal platelets - small platelets

ImmNE1 & ImmNE


reactive lymphs


Flow Cytometry

  • Technique for counting, examining and sorting microscopic particles suspended in a stream of fluid.
  • It allows simultaneous multiparametric analysis of the physical and/or chemical characteristics

Examples of parameters in flow cytometry


Flow cytometry - volume

  • Measures Total Cell Volume (size)
  • Direct Current Impedance

Flow cytometry - conductivity

  • Measures Internal Cell Structures such as nucleus and granules
  • radiowaves or other high wave frequencies

flow cytometry - light scatter

Measures Cell Surface Granularity Using a Broad Range of Angles.

Sysmex system

Direct current (Impedance) technology with hydrodynamic focusing

Fluorescent flow cytometery:

  • Fluorescent stain – nucleic acid and cytoplasmic organelles
  • Measures fluorescence and side angle light scatter to differentiate cells

Sysmex WBC measurements


  • forward scatter (SIZE)
  • side scatter (internal composition)
  • side fluorescence of the WBC populations (additional info on granularity and size)

Mean platelet volume

7.5-11.5 fL

abn rbc - cold agglutinins

abn rbc- macrocytic

abn rbc - does not start at baseline

could be schistos, micro, nrbcs, giant plts

abn rbc - two cell populations