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Microscopy of the Root Tip

Remember, apical meristems are found in buds and root tips. Since parenchyma cells are the only cells capable of mitotic division, apical meristems always contain many parenchyma cells in various stages of mitotic activity. The goal of these cells is to produce identical new cells to fuel growth. Root tips and buds are sites of new growth.

Parenchyma cells, products of root apical meristems, enlarge and elongate here to literally force the root tip through the soil. As root growth occurs, sand and other particles of soils abrade surface cells. A root cap typically forms for protection. The root cap provides a continuous supply of expendable parenchyma cells that lie over the meristematic tissues. At 100x magnification, the root cap is visible as layers of larger, less-organized parenchyma cells covering the meristematic region. Now, roll over the boundary between the apical meristem and root cap!

Note how the cells above(left of) the apical meristem region are darker and arranged in columns. The cells in this area are rapidly dividing, primarily in a single plane to form columns of cells. Cells within the columns elongate and this pushes the root tip through the soil.

At 400x magnification, cells are sufficiently resolved to reveal their type and stage of mitosis. Note that all cells are parenchyma types with large nuclei. Large nuclei are typical of cells that are replicating DNA prior to division. To lower right of center look for cells with chromosomes. Remember, chromosomes only become visible during various stages of mitosis or meiosis. These cells are dividing!

A 1000x view of the root tip within the meristem shows cells in various stages of mitotic activity. Link to the mitosis module now if you would like to view mitotic stages with some introductory information about events associated with each..

 

At 200x magnification, organized cellular columns that promote elongation are visible. To the left are transition zones where cells elongate and thereafter differentiate into more specialized cell types. These are subsequently called zones of elongation and differentiation respectively.

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Take a Closer Look!

Move the mouse here to view the tissue at 200x magnification.

Move the mouse here to view the tissue at 400x magnification

Rest the mouse here to view the tissue at 1000x magnification

Roll over the root-tip to get back to the module beginning!

Forward to the next topic.

Back to the module outline.