Hultcrantz M
Scand Audiol Suppl. 1985;24:1-24.
The function and morphology of the vestibular and cochlear parts of the inner ear have been examined after prenatal irradiation on the 12th, 13th and 16th gestational days in the CBA/CBA mouse. Irradiation was performed with a 0.5, 1 or 2 Gy single dose, whole body irradiation of the pregnant female. The irradiated fetuses were born after full term pregnancies and reached maturity (were 1--2 months old) before inner ears were analyzed with regard to vestibular tests, auditory thresholds and morphology. Morphology was studied by light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Auditory function was analyzed by frequency specific auditory brainstem response (ABR). Irradiation doses exceeding 2 Gy caused death to the pregnant female, abortion or malformed litters which were eaten by their mothers. Doses of 0.5, 1 and 2 Gy caused malformed cristae ampullares and maculae utriculi, in particular after exposure on the 12th or 13th gestational days. After those doses no abnormality of clinical behaviour of the animals was found. Ultrastructurally, type I hair cells (HC) of the vestibular part seemed more vulnerable to irradiation than the type II HC while the outer (OHC) and inner (IHC) hair cells appeared equally vulnerable. The ultrastructural changes of hair cells were predominantly localized to the hair cell surface showing a defect cuticle which was sometimes malformed and bulging. Sensory hair fusion occurred with a resulting poor maturation of sensory hair rootlets. The efferent nerve endings were estimated to be reduced in number but, if present, they had a normal ultrastructure. Otoconia showed severe morphological damage following irradiation particularly if exposed on the 16th gestational day. Malformed and fused otoconia were frequent having a disarrayed matrix. The irradiation induced morphological alterations in vivo could be reproduced in the in vitro systems. In addition, a retarded growth of the in vitro developing inner ear anlage was estimated to be the same for the vestibular and cochlear parts. The cochlear part of the inner ear showed a dose and age dependent hearing loss following irradiation. A shift of the ABR threshold was recorded in all exposed groups that were irradiated with 2 Gy. A correlation was found between the individual ABR-audiograms and the degree of morphological HC damage in the cochlea along the basilar membrane. The 12th gestational day inner ear anlage was most vulnerable to irradiation. The 13th gestational day inner ear was almost equally vulnerable and showed a dose-response relationship.(ABSTRACT TRUNCATED AT 400 WORDS)
在CBA/CBA小鼠妊娠第12、13和16天进行产前辐照后，对内耳的前庭和耳蜗部分的功能及形态进行了检查。对怀孕母鼠进行0.5、1或2 Gy单剂量全身辐照。辐照后的胎儿足月出生，并在对内耳进行前庭测试、听觉阈值和形态分析之前达到成熟（1 - 2月龄）。通过光学显微镜（LM）、透射电子显微镜（TEM）和扫描电子显微镜（SEM）研究形态。通过频率特异性听觉脑干反应（ABR）分析听觉功能。超过2 Gy的辐照剂量导致怀孕母鼠死亡、流产或产仔畸形，被母鼠吃掉。0.5、1和2 Gy的剂量导致壶腹嵴和椭圆囊斑畸形，特别是在妊娠第12或13天暴露后。给予这些剂量后，未发现动物有临床行为异常。超微结构上，前庭部分的I型毛细胞（HC）似乎比II型HC更容易受到辐照影响，而外毛细胞（OHC）和内毛细胞（IHC）似乎同样易受影响。毛细胞的超微结构变化主要局限于毛细胞表面，表现为角质层缺陷，有时畸形且凸起。感觉毛融合，导致感觉毛小根成熟不良。传出神经末梢数量估计减少，但如果存在，其超微结构正常。耳石在辐照后显示出严重的形态损伤，特别是在妊娠第16天暴露时。畸形和融合的耳石很常见，基质排列紊乱。辐照在体内诱导的形态改变可在体外系统中重现。此外，估计体外发育的内耳原基的生长迟缓在前庭和耳蜗部分是相同的。内耳的耳蜗部分在辐照后显示出剂量和年龄依赖性听力损失。在用2 Gy辐照的所有暴露组中均记录到ABR阈值的变化。发现个体ABR听力图与沿基底膜的耳蜗中形态学毛细胞损伤程度之间存在相关性。妊娠第12天的内耳原基最易受辐照影响。妊娠第13天的内耳几乎同样易受影响，并显示出剂量反应关系。（摘要截于400字）
