From Murine to Human Nude/SCID: The Thymus, T-Cell Development and the Missing Link

Figure 1

Steps of T-cell development. The lymphoid progenitor cell goes into the thymus through the cortico-medullary junction. DN thymocytes (CD4⁻CD8⁻) migrate across the subcapsular region and then the outer cortex. Interaction between DN cells and cTECs generates DP thymocytes (CD3⁺CD4⁺CD8⁺). Positively selected thymocytes interact with mTECs to complete the maturation process. In the medulla, self-reactive thymocytes are deleted, SP (CD3⁺CD4⁺ or CD3⁺CD8⁺) thymocytes are generated, and, eventually, the export of mature T cells from the thymus takes place.