Biology of the Mouse Histocompatibility-2 Complex

Somewhere I heard a story of a bridge and a painter. The bridge was enormous and was made all of metal, and the painter''s job was to keep it from rusting. He would start at one end and slowly proceed, day by day, month by month, toward the other end, painting the bridge. But no sooner would he finish with the painting than the bridge would begin to rust again. The rust, too, would start at one en...