Deficient T-cell development and apoptosis in thymus of Slug-deficient mice.

Histologic examination was performed on thymus sections from 4-week-old Steel mutant (Sl/Sl^d), W mutant (W/W^v), wild-type (control), and homozygous mutant (Slug−/−) mice. All sections were stained with hematoxylin and eosin. The normal architecture of control thymus shows the presence of well-defined cortical and medullar regions. This organization is lost in Sl/Sl^d, W/W^v, and Slug−/− mice. Matched sections from Slug −/− and control mice were subjected to DAPI and TUNEL assay. Increased apoptosis in Slug-deficient animals correlated with thymus atrophy, where the weight of Slug−/− thymus was reduced by approximately 35% compared with that of wild-type mice. On the left, representative analysis of the cells present in the thymus of these mice is shown. Cells isolated from a wild-type (control), a heterozygous mutant (Slug+/−), a homozygous mutant (Slug−/−), a Steel mutant (Sl/Sl^d), and a W mutant (W/W^v) mouse were stained with the monoclonal antibodies and analyzed by flow cytometry. The percentage of cells is indicated.