Final answer:
The __ produced by thymus epithelial cells, necessary for eliminating T cells that react to many self-antigens expressed only in peripheral tissues during negative selection, is the positive selection process in the thymus.
Step-by-step explanation:
The __ produced by thymus epithelial cells, necessary for eliminating T cells that react to many self-antigens expressed only in peripheral tissues during negative selection, is the positive selection process.
In the thymus, the positive selection process occurs in the cortex and involves the development of a functional T-cell receptor (TCR). Thymocytes with defective TCRs are eliminated by apoptosis. Those thymocytes that can interact appropriately with MHC molecules in the cortex receive positive stimulation and move further in the maturation process.
For example, thymocytes that bind to MHC molecules present on thymic epithelial cells are selected to move forward, while those that cannot bind undergo apoptosis.