Protoplast. Coloured scanning electron micrograph (SEM) of a tobacco plant (Nicotiana tabacum) protoplast. A protoplast is a plant cell that has had its tough outer cell wall removed by chemical treatment. This leaves an intact cell with its contents surrounded by its plasma membrane. The cell wall can later be regrown. The dimples on this protoplast are due to contraction of the outer membrane during drying. Each dimple corresponds to the position of a chloroplast. Protoplasts are used instead of intact cells in plant genetic engineering as they are easier to manipulate. Magnification: x3600 when printed 10 centimetres tall.