研究证明,真核细胞浆中的微核主要由染色体的断片演化而来,即诱变因子所致的染色体断裂,如不能愈合即形成无着丝点断片。此种断片虽具有合成 DNA 的能力,但进入有丝分裂后期时,由于脱离了着丝点,就不能被纺锤体牵向两极而纳入子核中,结果形成游离于胞浆的微核。不少作者发 Studies have shown that the micronuclei in eukaryotic cell cytoplasm are mainly evolved from fragments of chromosomes, that is, chromosome breakage caused by mutagenesis factors. If they do not heal, they form a non-centromerous segment. Although this kind of fragment has the ability to synthesize DNA, when it enters the late mitosis, it can not be caught in the daughter nucleus by the spindle due to its detachment from the centromere. This results in the formation of micronuclei free from cytoplasm. Many authors send