Ocular coloboma is sometimes accompanied by corectopia in humans and therefore ectopic pupil may indicate ocular coloboma in experimental animals. The RCS strain of rats has a low incidence of microphthalmia. We found that inferior ectopic pupil is associated exclusively with small-sized eyes in this strain. The objective of the current study was to evaluate whether inferior ectopic pupil is associated with iridal coloboma and other types of ocular coloboma in RCS rats. Both eyes of RCS rats were examined clinically, and those with inferior ectopic pupils underwent morphologic and morphometric examinations. In a prenatal study, coronal serial sections of eyeballs from fetuses at gestational day 16.5 were examined by using light microscopy. Ectopic pupils in RCS rats were found exclusively in an inferior position, where the iris was shortened. Fundic examination revealed severe chorioretinal coloboma in all cases of inferior ectopic pupil. The morphologic characteristics closely resembled those of chorioretinal coloboma in humans. Histopathologic examination of primordia showed incomplete closure of the optic fissure in 4 eyeballs of RCS fetuses. Neither F-1 rats nor N-2 (progeny of RCS x BN matings) displayed any ocular anomalies, including ectopic pupils. The RCS strain is a suitable model for human ocular coloboma, and inferior ectopic pupil appears to be a strong indicator of ocular coloboma.
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机译：眼球状结肠癌有时在人类中伴有黑眼症，因此异位瞳孔可能表明实验动物眼球状结肠癌。大鼠的RCS菌株的小眼症发生率较低。我们发现下异位瞳孔仅与该菌株中的小眼睛相关。本研究的目的是评估RCS大鼠下异位瞳孔是否与虹膜淋巴瘤和其他类型的眼淋巴瘤相关。对RCS大鼠的两只眼睛进行了临床检查，对异位瞳孔较弱的大鼠进行了形态学和形态学检查。在一项产前研究中，使用光学显微镜检查了妊娠第16.5天胎儿的眼球冠状连续切片。 RCS大鼠的异位瞳孔仅位于虹膜缩短的下位。眼底检查发现所有下异位瞳孔病例均出现严重的脉络膜视网膜炎。形态特征与人的脉络膜视网膜结肠炎十分相似。原基的组织病理学检查显示，RCS胎儿的4个眼球中的视裂未完全闭合。 F-1大鼠和N-2（RCS x BN交配的后代）均未显示任何眼部异常，包括异位瞳孔。 RCS菌株是人类眼球瘤的合适模型，下异位瞳孔似乎是眼球瘤的有力指标。
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