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Parenchyma Cells and Tissues

This image of parenchyma cells was used earlier to emphasize vacuoles. The term "parenchyma" was also introduced in the plastid unit. Keep in mind parenchyma cells possess thin primary cell walls. Large vacuoles can make these cells appear empty when stained but they are hardly non-functional in the living plant tissues. Note the abundant intercellular spaces that are typically present. These are sites of apoplastic transport.

Parenchyma are the most abundant cell type. You should expect to find these in all plant parts. In leaves and stems parenchyma are the only photosynthetic cells. When filled with chloroplasts, they are called chlorenchyma. Parenchyma cells are better suited for photosynthetic activity because their thin primary cell walls allow more efficient passage of light, water, gases, and metabolites. Remember, as walls of cells become thicker, transport processes are affected!

You might also recall parenchyma are the only cells that can engage in mitotic divisions. Subsequently, they are the only type of cell found in apical meristems. Some of these are shown in various stages of division in the mitosis unit.

In roots or stems parenchyma cells can be found as storage cells filled with starch. Some of these were shown in the plastid module. Watch for these in the Ranunculus root microscopy unit!

Specialized parenchyma is found in aquatic plants that require flotation for their leaves. The open, air-filled parenchyma tissue in these leaves is called aerenchyma.

Roll your mouse over the triangular intercellular space next to the round nucleus.