Figure 2.

A:

Comparison of apoptosis induced by 5 Gy of ionizing radiation in the epidermis (a–d) and hair follicles (e–h) from unirradiated (a and e) and irradiated (b and f) normal mice, irradiated p53-null mice (c and g) and irradiated p21-null mice (d and h). These skin sections were tested with the TUNEL assay using a fluorescein-conjugated antibody for detection. Sections were counterstained with propidium iodide. Sections from unirradiated p53-null and p21-null control mice are not included because they were not different from sections of unirradiated normal mice. The epidermis is indicated by arrowheads; apoptotic nuclei (stained green) in hair follicular matrix are indicated by arrows. B: Alopecia at 14 days after irradiation (5 Gy) in p53-sufficient mice but not in p53-null mice.