1.在病区饲养小鼠传代,从第三代起始至第八代,在二月龄小鼠,均可见甲状腺明显肿大、充血、增生。从第九代起,以及以后的第十代、第十一代,甲状腺明显变小,肉眼观察,已不易辨认。光镜及电镜下,可见甲状腺滤泡上皮分 1. The mice were passaged in the ward, from the third generation to the eighth generation, in the two-month-old mice, can be seen significantly enlarged thyroid, congestion, hyperplasia. From the ninth generation onwards, and after the tenth generation, the eleventh generation, the thyroid was significantly smaller, with the naked eye, has been difficult to identify. Light microscope and electron microscope, thyroid follicular epithelium can be seen