Persistent DNA Damage after High Dose In Vivo Gamma Exposure of Minipig Skin
Figure 5
Acute IR exposure of the skin leads to caspase-dependent apoptosis.
(A) TUNEL staining renders the epidermis largely positive for fragmented DNA in control (con) and (B) 50Gy-exposed skin sections (4 h post IR). (C-F) Immunofluorescence for activated-caspase 3 (a.casp.3; red) and γ-H2AX (green). Nuclei are counterstained with DAPI (blue). (C) Unirradiated control is largely lacking activated caspase 3-positive cells. (D) Three days post IR numerous activated-caspase 3-positive cells are present in the basal layer of the epidermis. (E) At 28 days post IR only few cells are positive for activated caspase 3. (F) 98 days post IR activated-caspase 3-positive cells often occur in the spinous layer of the epidermis (nuclei, blue) relative to the earlier time points. Activated-caspase 3-positive apoptotic cells at late time points often are also strongly positive for γ-H2AX nuclear staining (green; yellow due to signal overlap). Magnification bar: 20 µm.