Endodermis Part Deux How the Casparian Strip got its Stripes


An Endodermal cell seen with an Electron Microscope. It looks like a Parenchyma cell except that there are no large Plastids. Note the Circles on the Radial Walls of the right-hand image above! Ct = Cortical Cell; GS = Gas Space; Pc = Pericycle Cell (The Pericycle is a layer(s) of parenchyma-like cells which is located between the endodermis and the Vascular tissues of the Stele); T = Tonoplast, V=Vacuole

Same as above but Labeled to show the location of the Casparian Strip!

High Magnification view of the Casparian Strip (CS) as seen with an Electron Microscope. Note that the dense material permeates the entire cell wall and middle lamella of both cells. This is due to the presence of Suberin. The Plasmalemma is firmly attached to the CS. The black globules are in the Vacuole and are touching the Tonoplast. Locate the Cytoplasm and the Plasmalemma!

In the Absence of a Casparian Strip, Solute Molecules would become equally concentrated on each side of the Endodermis.

The Endodermis can exclude solute molecules if the Plasmalemma is impermeable to them. Alternatively, it can also accumulate molecules against a concentration gradient with the expenditure of ATP. Thus, it helps to create concentration gradients. Concentration gradients are important for the control of water uptake and transport, and it all starts right here at your friendly neighborhood Casparian Strip!