Lebedeva L I, Chubykin V L
Genetika. 1975;11(3):29-36.
It is shown by the study of the location of acentric fragments of chromosomes at metaphase and anaphase in the root cells of pea (cultivar "Capital"), in the cornea of rats (strain Wistar), in the bone marrow of mice (strain BALB), in the cultures of embryonic fibroblasts of mice (strain C57B1) and of embryonic human fibroblasts that some fragments are situated outside the equatorial plates, while others are situated within the plane of the equatorial plate. The fragments of the first type initiate mainly spontaneously, while the fragments of the second type are mainly induced by irradiation. These principles are observed in all the types of animal and plant cells studied. The location of the fragments observed in non-radiated cells could be explained if it be assumed, that all the chromosome breaks are realized before the prometaphase and by the beginning of the prometaphase the fragments are randomly distributed within the volume of the nucleus. At the prometaphase most fragments move from the equator to the pole of the cell and thus at the metaphase and anaphase are found to be located outside the equatorial plate. For the explanation of the observed ratio of the two types of fragments in an irradiated cell it is assumed that chromosome fragments resulting from breaks induced by irradiation are completely detached from chromosomes only after the beginning of the prometaphase. Possibly, the process of development of breaks is also not yet completed by this time, it continues and is completed at the metaphase, partially, at the anaphase of the mitosis.
通过对豌豆（品种“Capital”）根细胞、大鼠（Wistar品系）角膜、小鼠骨髓（BALB品系）、小鼠胚胎成纤维细胞培养物（C57B1品系）以及人类胚胎成纤维细胞培养物中期和后期染色体无着丝粒片段位置的研究表明，一些片段位于赤道板之外，而另一些片段则位于赤道板平面内。第一类片段主要自发产生，而第二类片段主要由辐射诱导产生。在所有研究的动植物细胞类型中都观察到了这些规律。如果假设所有染色体断裂都在前期之前发生，并且到前期开始时片段在细胞核体积内随机分布，那么就可以解释在未辐射细胞中观察到的片段位置情况。在前期，大多数片段从赤道向细胞两极移动，因此在中期和后期会发现它们位于赤道板之外。为了解释在辐射细胞中观察到的两种片段比例情况，假设由辐射诱导产生的断裂所形成的染色体片段仅在前期开始后才完全从染色体上分离。可能此时断裂的发展过程也尚未完成，它会继续并在有丝分裂的中期部分完成，在后期完成。
