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Figure 4b. Disappearance of the thymus after irradiation in an 8-week-old infant with "symptoms of thymic enlargement," according to the original caption. (a) Arrows in an initial frontal radiograph point out "atelectasis" of the right lung and accompanying thymic enlargement, an appearance that today is recognized as a normal finding due to the thymus gland. (b) Radiograph obtained 5 weeks after thymic irradiation (dose not given) shows that the thymus is notably smaller; the original noted that the child "is now enjoying perfect health." (Reprinted, with permission, from reference 28.)