31. We already know such transplants work in people who are born without a thymus . 32. Ferrer said before going into surgery Wednesday for removal of an enlarged thymus gland. 33. The team has found a way to introduce foreign cells into newly grown thymuses . 34. The thymus is present in all immune responses. 35. They are an outbred strain that has an intact thymus and normal immune system. 36. Approximately 99 percent of pre-T cells within the thymus are negatively selected. 37. Unlike other lymphoid lineages, T cell development occurs almost exclusively in the thymus . 38. Afterward some T cells leave the thymus to migrate to the skin and mucosae. 39. This receptor protein preferentially expresses in the thymus . 40. The avian T cell population, like that of mammals develops in the thymus .