The cells shed by the root cap of Zea: their origin and some structural and physiological properties

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Abstract
Two populations of living detached cap cells are found within the drop of mucilage at the root tip of a 3‐d‐old corn seedling. Axial cells, which pass through the length of the columella, are shed at the apex of the cap and lateral cells, which have spent less time or no time within the columella, are detached from the cap flanks. The two types of cells differ in shape, size and internal structure. Whereas the axial cells are more or less spherical and have a projected surface area of 1300μm2, the lateral cells are elongated and possess a projected surface area of 2000μm2. The axial cells are further distinguished by the association with a polyhedric net thought to be remnants of undigested middle lamellar material from the columellar tissue. Both populations of cells arc metabolically active and can be plasmolysed, but no evidence was found that they secrete mucilage after detachment. The lateral cells have been cultured on solid nutrient media and on nutrient‐free agar. In both cases, they did not divide; however, they enlarged by one‐third in their projected surface area over 15 d.