Fig. 5. Light micrograph of longitudinal section through tissue undergoing dedifferentiation during generation of new phellogen after mechanical wounding of bark of healthy 2-year-old peach bark. Outside bark in all figures is oriented toward top of plate. Bar = 10 microns. Fig. 5 shows section of differentiated phellogen (PG) and incipient impervious tissue (IT and arrows) 96 hr postwounding.