Stage-specific changes in fetal thymocyte proliferation during the CD4-8- to CD4+8+ transition in wild type, Rag1-/-, and Hoxa3,Pax1 mutant mice

Background  

The function of the thymic microenvironment is to promote thymocyte maturation, in part via regulation of thymocyte proliferation and cell death. Defects in fetal thymic epithelial cell (TEC) development and function, and therefore in the formation of a functional microenvironment, can be caused either directly by TEC differentiation defects or indirectly by defective thymocyte maturation. In this paper we studied fetal thymocyte proliferation during the early transition from the CD3^-4^-8^- (triple negative, TN) to CD4⁺8⁺ (double positive, DP) stages. We compared wild type mice with Rag1 ^-/- mice and with Hoxa3 ^+/- Pax1 ^-/- compound mutant mice, which have blocks at different stages of thymocyte development.