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Passage cells are important in growth and development. As the plant ages and growth slows, the number of Passage cells begin to decrease, eventually resulting in a complete lack of passage cells altogether. In response to dehydration, some passage cells particularly those located in aquatic environments have developed pads that are composed of lignin and cellulose and are designed to close the cells to prevent further loss of ions and water to the environment via diffusion.

Changes in response to external Stimuli
Being heavily involved in water uptake and regulation of solutes into and out of the membrane, it is understandable that the Exodermal cells must be able to adapt to their external environment to ensure that the plant can survive. Exodermal cells have the ability to modify their Casparian Bands to fit changing stimuli. Exodermal barriers can change their permeability as necessary to ensure that adequate nutrients are reaching the plant. In microenvironments, where macronutrient levels are low (such as phosphorous, nitrogen and potassium) development in the Exodermis, Casparian bands and the Suberin Lamellae In areas with high-stress conditions such as heavy metal concentration, high salt concentration and other inorganic compounds, the exodermal cells are wider, ensuring that these toxic components are not able to enter the root complex and cause damage to the system.

In environments with low water supply, such as in drought or desert conditions, the deposit of tertiary layers in the plant's exodermis can be found up far higher in the apex of the root system.

In areas with a high water environment such as wetlands and in areas that are predominantly anaerobic or hypoxic, plants Exodermis layers were found to develop patchy Exodermal layers to aid the diffusion of oxygen into the root system more effectively.

From the Stub