Effect of monoenergetic neutron irradiation on the postnatal development of the cochlea in C3H/HeN mice.
To investigate the toxic effect of neutrons at energies of approximately 1MeV on the ear, we exposed 7-day-old mice to 1.0 Gy of monoenergetic neutrons (1.026 MeV) or (137)Cs gamma rays, and assessed subsequent morphological changes in the inner ear by light and scanning electron microscopy. Monoenergetic neutrons, but not gamma rays, caused acute changes in the ear. The epithelium of the greater epithelial ridge in the organ of Corti had disappeared by 72 hr post-irradiation, as a result of epithelial apoptosis observed 6 hr post-irradiation. Radiation could induce apoptotic cell death of the epithelium of the greater epithelial ridge at 3 or 4 days of age. Protruding structures were detected on the surface of the hair cells by 72 hr post-irradiation. The neutron-irradiation also caused the apoptotic cell death of epithelial cells at the nasal conchae, and subsequent acute otitis media continued until 10 weeks of age.
Nitta
Yumiko
Y
International Radiation Information Center, Research Institute for Radiation Biology and Medicine, Hiroshima University, Japan.
Araki
Nobukazu
N
Nitta
Kohsaku
K
Harada
Toshihide
T
Ishizaki
Fumiko
F
Cheng
Weiping
W
Ando
Juko
J
D000367:Age Factors; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002588:Cesium Radioisotopes; D003051:Cochlea / Q000254:growth & development* / Q000528:radiation effects* / Q000648:ultrastructure*; D004848:Epithelium / Q000528:radiation effects; D005720:Gamma Rays / Q000009:adverse effects*; D051379:Mice; D008809:Mice, Inbred C3H; D008855:Microscopy, Electron, Scanning; D009296:Nasal Cavity / Q000528:radiation effects; D009502:Neutrons / Q000009:adverse effects*; D011839:Radiation, Ionizing
D002588:Cesium Radioisotopes