Exercise 1.9 - The Phase Contrast Microscope

LEVEL II

Materials

Procedure

  1. Establish Koehler illumination on the microscope. If the instructor approves, center the phase annular ring and its corresponding phase plate.

  2. Make a simple wet mount of the amoeba and observe under bright field microscopy at 10X.

  3. Locate an active amoeba and center it in the field of view. Rotate the condenser phase ring to match the 10X phase with the 10X objective.

  4. Observe the difference in the appearance of the amoeba between normal bright field and phase contrast.

  5. Draw the amoeba viewed under phase contrast. Label organelles which are more clearly visible with phase contrast than with bright field microscopy.

  6. Return the phase control on the condenser to the normal bright field setting, switch to a higher magnification (20X or 40X) and observe the amoeba at the higher magnifications with and without phase enhancement.

  7. Compare the view of the amoeba under phase contrast, normal unstained bright field and darkfield (Exercise 1.8) with the view of the prestained commercial preparation of Amoeba proteus. List the organelles and/or structures which are more clearly demonstrated by each optical technique.

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Drawing of amoeba observed with phase contrast optics

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Cell Biology Laboratory Manual
Dr. William H. Heidcamp, Biology Department, Gustavus Adolphus College,
St. Peter, MN 56082 -- cellab@gac.edu