100x Magnification
In this 100x view, the endodermis is distinctive as a layer of irregularly thickened cells lying between the parenchyma cells of the cortex to the right and vascular tissues and parenchyma cells of pith to the left. Vascular tissues with xylem and phloem form a concentric ring just inside the endodermis. The Casparian strip of the endodermis is a diagnostic feature of most roots that is clearly visible here.
200x Magnification
In this 200x view, thin-walled parenchyma cells of the cortex now stand in contrast to the cells of the endodermis with its prominent Casparian strip. The Casparian strip consists of suberized cell surfaces that seal off all intercellular spaces between cells of the cortex and vascular tissues. Transport of water into the root will occur across rather than between cells. Solutes can therefore be controlled. Note that the thick secondary walls of xylem are visible now just interior to the endodermis as are nuclei of companion cells in the phloem.
400x Magnification
In this 400x view, the parenchyma cells of phloem are now visible between the endodermis and xylem. Locate the nucleated companion cells! The thick secondary walls of some xylem cells are visible just to the left of the thin-walled parenchyma cells of phloem. Note how the vascular tissues form a ring with xylem tissues alternating with phloem.
1000x Magnification
In this 1000x view, cells of the endodermis clearly show the uneven suberized thickenings of the Casparian strip. Remember, the Casparian strip restricts flow of water and solutes between cells. Water and solutes therefore only enter the root across membranes of endodermal cells. Selective transport processes in these membranes control what substances enter vascular tissues as solutes. Note the thin cell walls of the parenchymatous phloem and the nuclei of companion cells visible here!
In this low magnification (40x) view of a Corn prop root, some typical attributes of a monocot root are visible. There are smaller, thicker walled cells just below the epidermis. These are supportive collenchyma cells. The cortical tissues between the epidermis and endodermis are mostly large parenchyma cells as are those of the pith in the innermost part of the root. The endodermis with its Casparian strip is just outside a circular ring of vascular tissues. The large open circular cells are vessels of the primary xylem.
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