After surviving the cortex, where do T cells move next?

• A. Back into the bloodstream
• B. Directly to peripheral tissues
• C. Into the medulla
• D. To the spleen only

Answer: (C)

The movement of T cells after they have undergone maturation in the cortex of the thymus involves transitioning into the medulla. During their time in the cortex, T cells undergo selection processes, which includes positive and negative selection to ensure that only those that can recognize self-MHC molecules and are not auto-reactive are allowed to survive. Once they progress past this selection phase, they migrate into the medulla of the thymus.

In the medulla, T cells receive further maturation signals and undergo additional selection. This area contains specialized cells that test the T cells' reactivity to self-antigens, ensuring a robust and self-tolerant immune repertoire before these cells leave the thymus. After completing their maturation process in the medulla, T cells will then enter the bloodstream or move to peripheral tissues, but their immediate next step is into the medulla of the thymus.