Like the thymus, the spleen possesses only efferent lymphatic vessels. Like the thymus, the spleen has only efferent lymphatic vessels. Other offal, such as blood, pancreas, spleen and thymus must be declared by name. Removal of the thymus in adults does not appear to induce immune deficiency. Many pathological findings are seen in the liver, thymus and other organs. They are an outbred strain that has an intact thymus and normal immune system. AIRE is a transcription factor expressed in the medulla (inner part) of the thymus. It contains the heart, esophagus, trachea, thymus, and aorta. The thymocytes and the epithelium of the thymus have different developmental origins. Within the thymus, T cells mature. T cells migrate to and mature in a distinct organ, called the thymus. Regulatory T cells are another type of T cell that mature in the thymus. These CLP cells then migrate via the blood to the thymus, where they engraft. If they settle in the thymus, they may develop into T cells. These mutations affect thymocytes developing within the thymus.