Milisen W B, Benjamin S A, Miller G K
Department of Pathology, Colorado State University, Fort Collins 80523.
Radiat Res. 1988 Jul;115(1):84-95.
Thymic explant cultures were used to study the radiosensitivity of nonlymphoid thymic components in dogs. Thymic fragments from fetal (50 days gestation), newborn, and juvenile (70 days old) dogs were irradiated in vitro at 0, 0.5, 1, 2, or 4 Gy prior to culture. Colonies were classified as epithelial, spindle, or mixed cell type, and colony numbers were counted and diameters measured. Radiation caused a significant dose-related decrease in the number of spindle cell colonies from all ages. There was a corresponding, but smaller, dose-related increase in the number of epithelial colonies. The diameter of spindle cell colonies also decreased with dose, and this was accompanied by a reduction in cell density. While epithelial colony diameters did not change consistently with dose, there was an overall reduction in cell density in these colonies. This was more severe in the fetal than in the juvenile cultures. These results indicate that the putative mesenchymal (spindle cell) components of the thymus are significantly more radiosensitive than the epithelium at all ages and that fetal epithelium is more sensitive than epithelium from postnatal animals. This suggests that radiation-induced thymic epithelial defects reported after prenatal irradiation could be due to a combination of direct epithelial injury and defective inductive interaction between epithelium and the more radiosensitive mesenchyme.
胸腺外植体培养用于研究犬非淋巴细胞性胸腺成分的放射敏感性。来自胎儿（妊娠50天）、新生犬和幼年犬（70日龄）的胸腺片段在培养前于体外接受0、0.5、1、2或4 Gy的照射。菌落被分类为上皮型、纺锤型或混合细胞型，并计数菌落数量和测量直径。辐射导致所有年龄段的纺锤细胞菌落数量出现显著的剂量相关减少。上皮菌落数量有相应的但较小的剂量相关增加。纺锤细胞菌落的直径也随剂量减小，同时细胞密度降低。虽然上皮菌落直径并不随剂量一致变化，但这些菌落中的细胞密度总体降低。这在胎儿培养物中比在幼年培养物中更严重。这些结果表明，胸腺假定的间充质（纺锤细胞）成分在所有年龄段都比上皮细胞对辐射敏感得多，并且胎儿上皮比出生后动物的上皮更敏感。这表明产前照射后报道的辐射诱导胸腺上皮缺陷可能是由于上皮直接损伤以及上皮与更敏感的间充质之间诱导相互作用缺陷的综合作用。
