LN stroma lacks Wnt4 and Wnt7b transcripts. The mRNA expression profile of selected genes in the stroma of wt thymus and LNs, OM⁺ LNs, and OP9-DL1 cells. The mRNA values were normalized according to Hprt and thymic stroma mRNA levels were set as 1. Data are mean ± SD from 3 or 4 independent experiments (*no detectable mRNA after 50 amplification cycles). Differences between groups were evaluated with Student t test. Levels of statistical significance for comparison of wt thymus versus wt LNs are ¥P < .04, §P < .005, and ‡P <.001. †Levels of DL1 transcripts for OP9-DL1 cells (715 ± 55) are not shown on the graph.