Differentiation arrest of lymphoid progenitors in Pten mutants.Rag1 is expressed in lymphocytes and highlights the thymus. Representative lateral and dorsal views of wild-type (A-B) and Pten mutant embryos (C-D) are shown; close-ups of the thymus in the insets. (E) Rag1⁺ area in wild-type and Pten mutant embryos at 5 dpf was quantified and is depicted in scatter plot; wild-type, n = 14; Pten mutant (mt), n = 11. The average rag1⁺ area is highlighted with a red bar and is significantly reduced in Pten mutants (P < .001, 2-tailed t test). (F-I) Ikaros was used as a marker for lymphoid progenitors in 5-dpf wild-type (F,H) and Pten mutant embryos (G,I) in the thymus and CHT, respectively; thymus is indicated with arrowhead. Representative embryos are depicted with anterior to the left. Scale bars in panels D and I represent 200 µm. wt, wild type.