The Mouse Thymus Normally Contains About 1–2 X 108 Thymocytes $\alpha$

Essay

The mouse thymus normally contains about 1–2 x 108 thymocytes, the vast majority of which are CD4+CD8+ (double-positive) cells. When thymocytes from mice with a gene deficiency in the TCR $\alpha$ locus are compared with those from TCR $\beta$ -deficient mice, a striking difference between the two different knockout lines is observed, as shown in Figure in a simplified version of flow cytometry data. The numbers of thymocytes in each thymus is indicated below the plots.

-Which region of the thymus organ would show a dearth of developing thymocytes in the TCR $\alpha$ ^-/- thymus? Which region in the TCR $\beta$ ^-/- thymus?