Word: thymuses
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Jacques F.A.P. Miller, has found what seems to be the secret of the thymus...
Shaped like a double pendant, the thymus in newborn babies weighs, on the average, one-third of an ounce. In two months it doubles in size, and in a twelve-year-old child it weighs an ounce or more...
...after that, 70% of the thymecto-mized group became lethargic, and wasted away, with ruffled fur and a hunched posture. They developed diarrhea and died within three weeks. Yet if thymus removal was postponed until the mice were a week or more old, they rarely developed these disorders-and never, if the operation was done after three weeks...
Proxy Immunity. To cross-check his findings, Dr. Miller took some newborn mice, removed their thymuses, and a week later grafted in new thymuses from mice of a different strain. These animals grew up to be healthy, but had a striking peculiarity. They accepted skin grafts from mice of the strain whose thymus glands they carried, while rejecting, in the normal way, other foreign tissues. Dr. Miller called it "immunological reactions by proxy." Despite the differences between man and mouse, the thymus gland probably plays much the same role in both species...
...Miller's work suggests that the human thymus, in the first weeks of life, produces the basic cells that are then distributed to other white-cell factories, in lymph nodes and the spleen, where cells can be mass-produced at short notice to protect the body against invading microbes or foreign tissue. Once the master cells have been distributed, the thymus seems to have done its main job. In adult life, and even in later childhood, the gland can be removed with little apparent effect. Perhaps it eventually becomes use less, despite its vital early role...