Cortex of the thymus from a child - details (400X)

In the cortex of the tymus, we find thymocytes (immature pre-T cells), thymic epithelial cells, and macrophages. It is not possible to distinguish between thymic epithelial cells and macrophages in this section.

Thymic epithelial cells contribute to T-cell maturation by presenting MHC molecules. T-cells are selected such that only those recognizing MHC molecules survive (positive selection). Among these, T-cells activated by self-MHC molecules are eliminated (negative selection). Thymic epithelial cells can also secrete hormones that stimulate T-lymphocyte maturation. As lymphocytes mature, they move closer to the medulla.