Cell Biology & Microscopy

Fixed Versus Live Specimens


Click on the image to enlarge
(640 KB).
Click on the image to view the movie
(live specimen enables time-lapse imaging, 2 MB, 12″)

A confocal microscopy image with fixed specimen. This is a C. elegans embryo with tubulin labeled in green.
A MPFE microscopy image with live specimen. This is a C. elegans embryo with GFP fused with tubulin.


The specimen is no longer alive and the tissue/cell structure has been preserved (usually chemically with formaldehyde or alcohols).

  • Advantages: the tissue can be stained to accentuate specific structures, the tissue is static. Specimens can be prepared in large numbers. The specimen can be re-analyzed at a later time.
  • Disadvantages: fixations can alter the tissue. You cannot see dynamic changes within the specimen.
  • Examples: 1) antibody-specific labeling, 2) ultra-structure analysis (e.g.: EM)


  • Advantages: dynamic changes within the specimen can be seen. It is likely to provide a truer representation of the phenomenon of interest.
  • Disadvantages: often can only visualize one specimen at a time (thus is more time consuming). The specimen can only be used once.
  • Examples: 1) GFP, 2) time-lapse (e.g.: DIC)

Common Cell Biology Techniques

Common Microscopy Techniques

Light Microscopy

A C. elegans embryo at pro-nuclei meeting stage (before dividing into 2-cell embryo)

Electron Microscopy (EM)

(Flash movie, 460K, movie length: 27″)

TEM specimen is a C. elegans embryo (cross-sectioned).
SEM specimen is a bunch of C. elegans (surface imaging).

Microscopy Bioclips

This bioclip illustrates commonly used microscopy in C. elegans research. It does not focus on the technical aspects of microscopes but rather emphasizes how each type of microscopy helps researchers observe biology events. Microscopies addressed are DIC, confocal, multiphoton, TEM and SEM. Computational processing, such as color mapping, used in current microscopy is also illustrated.

(A Flash movie, 50 MB, movie length: 19′ 44″)

EM.swf459.32 KB
Tubulin_GFP.mov2.44 MB