Figure 5
Chronological GFP expression changes after X-ray half-irradiation. (a) Immunohistochemical images of ex vivo testis tissues 1 h after 10 Gy X-ray 50% irradiation using X-ray microbeams. Staining for γ-H2AX, Anti-GENA and Hoechst is shown as red, green and blue, respectively. Scale bars, 500 μm. (b) Representative images showing Acr-GFP expression in single cultures of testes exposed to 5 Gy 50% irradiated X-ray microbeams obtained at 16, 18, 20 and 22 dpp. In the irradiation setting image, the irradiated area is shown as a red square. The Acr-GFP expression areas expanded from the non-irradiated to the irradiated areas due to the tissue-sparing effect. Scale bars, 500 μm. (c) Schematic representation of the two-step process of the tissue-sparing effect in spermatogenesis. First, spermatogonial cells survive in the non-irradiated areas, whereas they are eliminated in the irradiated areas after irradiation. The surviving cells then migrate to the irradiated area via the seminiferous tubules. Thus, the spermatogonial cells require these two steps, survival and migration, for an effective tissue-sparing effect in spermatogenesis.
