Alnus Rubra and the Nitrogen-Fixing Frankia RESULTS Bob Musgrove Biology 585 Scanning Electron Microscope Professor: Dr. Darlene Southworth Southern Oregon University   Introduction | Materials and Methods | Results | Discussion | Literature Cited The micrographs on this page are the results of following specimen preparation method D which is outlined in the previous section. The images were scanned with an Hitachi S-2100 SEM. Figure 4. Cross section of a single Alnus rubra root nodule. at low magnification. Note the 1 millimeter line scale.  Figure 5. Below is an overview of Alnus rubra root nodule structure. Note that most of the cell contents (cytoplasm, plastids, nuclei) appear to have been evacuated during specimen preparation. Barely visible in this image are individual starch amyloplasts clustered within the cell walls. The 100 micron line scale represents 0.1 millimeter.    Figure 6. The micrograph on the left illustrates the membrane-bound vesicles which enclose the Frankia alni. Note how the interior of the cell appears to be overflowing with vesicles ranging from 2.5 to 4.5 microns in diameter.  Figure 7. Frankia vesicles in a Alnus rubra root nodule specimen different from that used for the above three micrographs. Note the starch amyloplast, which is 8 microns in diameter, to the left of the line scale. The line scale represents 0.02 millimeter.      Introduction | Materials and Methods | Results | Discussion | Literature Cited web page authored by Bob Musgrove