The cells within the thymus include thymocytes and thymic stromal cells. Thymocytes are the precursors of T-lymphocytes, which are mainly located in the cortex of the thymus gland, and they are able to play an immunizing role in the body. The stromal cells of the thymus refer to the cells located inside the thymus that are not part of the thymus, also called non-thymic cells. They are mainly composed of epithelial cells, fibroblasts, macrophages, dendritic cells, mast cells and B lymphocytes. They are important for maintaining the morphology of the thymus and protecting it.