Marked increase in the rate of ocular lens regeneration in the newt, Cynops pyrrhogaster, following partial body exposure to low dose X-rays.
In recent years, concern over the stimulating effects of low-dose X-rays has been growing. Therefore, the effects of low-dose X-irradiation on lens regeneration in the newt were examined. Newts were subjected to sham or whole-body X-ray exposure at a dose of 0.2 Gy or 0.4 Gy, delivered at a rate of 0.43 Gy min(-1). The eyeballs were fixed in formalin solution, embedded in paraffin and assessed histologically. On day 14 after lens removal, unexposed animals showed the formation of a hollow epithelial vesicle of depigmented cells continuous with the laminae of the iris corresponding to the expected regeneration stage (Reyer's regeneration stage II). In contrast, lenses from newts exposed to a 0.2 Gy dose of X-rays showed some formation of the primary lens fibre nucleus corresponding to the fibre differentiation stage (Reyer's regeneration stage III-early). Thus, low-dose X-irradiation induced regeneration compared with the unexposed groups. An acceleration from Reyer's stage II to III-early was also found on day 14 following irradiation of only the upper belly, including the spleen. The effects of low-dose X-irradiation on lens regeneration may be mediated by changes in immune activity.
Okamoto
T
T
Department of Radiological Sciences, International University of Health and Welfare, Kitakanemaru 2600-1, Ohtawara-shi, Tochigi-ken 324-8501, Japan.
Kanao
T
T
Miyachi
Y
Y
Nohara
N
N
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D007908:Lens, Crystalline / Q000502:physiology / Q000528:radiation effects*; D012038:Regeneration / Q000528:radiation effects*; D012455:Salamandridae / Q000502:physiology*; D014916:Whole-Body Irradiation; D014965:X-Rays