cornsmic.htm

Microscopy of a monocot Stem

100x Magnification

The 100x view of this corn stem provides a better view of the vascular bundles. Notice the ring of sclerenchyma fibers that serve as supportive, protective tissues for the bundles. Just above the xylem in the "forehead" region of each bundle we will see phloem tissues at higher magnification.

200x Magnification

In moving to a 200x view, the sclerenchyma type cells of xylem and fibers are now beginning to stand out against the thin-walled parenchyma cells of cortical and phloem tissues. Take a close look at the parenchyma cell walls and compare thickness of these to the sclerenchyma fibers and xylem. Again, cell wall differences are important in the identification of these cell types.

400x Magnification

The 400x magnification field is positioned over the vascular bundle to provide a closer examination of the xylem and phloem. Note how the sclerenchyma fibers form a protective ring around the vascular bundle. This is called a bundle sheath. Some parenchyma cells are visible within the xylem and above these, phloem is identifiable as an entirely parenchymatous tissue type. Look for the larger diameter cells in phloem. These are sieve tube members and you should see nucleated companion cells next to these. Our next magnification will show these more clearly.

1000x Magnification

Finally, at 1000x magnification you are looking directly into the phloem. Nuclei of companion cells are clearly visible. Thick secondary walls of xylem vessels are just visible in the lower left and right corners of the image. See the differences in cell wall thickness?

The first thing you should note about this 40x image of a corn stem are the randomly arranged vascular bundles. This is in contrast to the circular arrangements of vascular bundles in dicot stems. The vascular bundles of corn look like miniature "clown" faces, a point that might help you remember this monocot stem. The eyes and noses of the faces are large xylem vessels. Supportive, protective sclerenchyma fibers can be seen associated with these bundles. Not visible at this magnification are the phloem tissues just above the xylem in the vascular bundles. Note the empty parenchyma cells making up the cortical tissues of this stem.

*Microscopy of a monocot* Stem 100x Magnification** The 100x view of this corn stem provides a better view of the vascular bundles. Notice the ring of sclerenchyma fibers that serve as supportive, protective tissues for the bundles. Just above the xylem in the "forehead" region of each bundle we will see phloem tissues at higher magnification. 200x Magnification In moving to a 200x view, the sclerenchyma type cells of xylem and fibers are now beginning to stand out against the thin-walled parenchyma cells of cortical and phloem tissues. Take a close look at the parenchyma cell walls and compare thickness of these to the sclerenchyma fibers and xylem. Again, cell wall differences are important in the identification of these cell types. 400x Magnification The 400x magnification field is positioned over the vascular bundle to provide a closer examination of the xylem and phloem. Note how the sclerenchyma fibers form a protective ring around the vascular bundle. This is called a bundle sheath. Some parenchyma cells are visible within the xylem and above these, phloem is identifiable as an entirely parenchymatous tissue type. Look for the larger diameter cells in phloem. These are sieve tube members and you should see nucleated companion cells next to these. Our next magnification will show these more clearly. 1000x Magnification Finally, at 1000x magnification you are looking directly into the phloem. Nuclei of companion cells are clearly visible. Thick secondary walls of xylem vessels are just visible in the lower left and right corners of the image. See the differences in cell wall thickness? The first thing you should note about this 40x image of a corn stem are the randomly arranged vascular bundles. This is in contrast to the circular arrangements of vascular bundles in dicot stems. The vascular bundles of corn look like miniature "clown" faces, a point that might help you remember this monocot stem. The eyes and noses of the faces are large xylem vessels. Supportive, protective sclerenchyma fibers can be seen associated with these bundles. Not visible at this magnification are the phloem tissues just above the xylem in the vascular bundles. Note the empty parenchyma cells making up the cortical tissues of this stem.



	Note: To magnify this image, move your mouse to the right and let it rest on an icon for each desired magnification.