Takada A, Takada Y, Huang C C, Ambrus J L
J Exp Med. 1969 Mar 1;129(3):445-57. doi: 10.1084/jem.129.3.445.
Whole-body irradiation of mice with 300 or 400 R causes a precipitous fall in thymus weight, followed by an increase in the mitotic index and an almost complete restoration of thymus mass. This phase is followed by a secondary fall in thymus weight and gradual recovery. This secondary fall can be prevented by intravenous injection of bone marrow or shielding of the hind limbs during irradiation. The hypothesis is proposed that the thymus depends on the migration of cells from the bone marrow to the thymus for the maintenance of its cell population. Bone marrow cells with chromosome markers injected intravenously into normal or lightly irradiated (150 R) animals do not populate the host bone marrow to any significant degree. After whole-body irradiation with heavy doses (400 R), donor cells dominate the marrow. There may be a competition between dividing cells in the bone marrow which regulates proliferation of hemic cells. Bone marrow cells with marker chromosomes do not repopulate the thymus in irradiated animals until long after repopulating the bone marrow. It is possible that these cells have to pass through the marrow or the blood-marrow barrier to acquire characteristics needed for entering the thymus. After whole-body irradiation with 500 R or more, the first phase of regeneration of the thymus, represented by an increase in the mitotic index, does not occur to a significant degree. Apparently cells in the thymus capable of proliferation have been largely eliminated, and restoration of organ mass depends chiefly on seeding from other sources, probably the bone marrow. After whole-body irradiation with 200 R, only the first phase of thymus weight loss and regeneration takes place. Probably bone marrow injury is too small to interfere with the supply of cells repopulating the thymus.
用300伦琴或400伦琴对小鼠进行全身照射会导致胸腺重量急剧下降，随后有丝分裂指数增加，胸腺重量几乎完全恢复。此阶段之后是胸腺重量再次下降并逐渐恢复。静脉注射骨髓或在照射期间对后肢进行屏蔽可防止这种再次下降。有人提出这样的假说：胸腺依赖于细胞从骨髓迁移至胸腺以维持其细胞群体。将带有染色体标记的骨髓细胞静脉注射到正常或轻度照射（150伦琴）的动物体内，这些细胞在很大程度上不会在宿主骨髓中定居。用大剂量（400伦琴）进行全身照射后，供体细胞在骨髓中占主导地位。骨髓中分裂细胞之间可能存在竞争，这种竞争调节血细胞的增殖。带有标记染色体的骨髓细胞在照射动物体内直到重新填充骨髓很久之后才会重新填充胸腺。有可能这些细胞必须穿过骨髓或血 - 骨髓屏障以获得进入胸腺所需的特性。用500伦琴或更高剂量进行全身照射后，以有丝分裂指数增加为代表的胸腺再生的第一阶段不会显著发生。显然，胸腺中能够增殖的细胞已被大量清除，器官重量的恢复主要依赖于其他来源的细胞植入，可能是骨髓。用200伦琴进行全身照射后，仅发生胸腺重量减轻和再生的第一阶段。可能骨髓损伤太小，不足以干扰重新填充胸腺的细胞供应。
