Assessment of stromal cell proliferation during posttransplantation LN reconstruction. (A) Stromal cells from pretransplantation (naive, gray line) inguinal LNs and reconstructed LNs (black line) were analyzed for EYFP expression on CD45⁻Pdpn⁺ stromal cells by flow cytometry. (B) Percentage of EYFP-expressing stromal cells within CD45⁻ cells (mean ± SEM; n = 6 LNs). **P < .01. (C) IL-7 mRNA expression as determined by RT-PCR analysis from CD45⁻ cells (mean ± SEM; n = 3 LNs). *P < .05. (D) Ki67 expression in transplanted IL-7–CrexR26-EYFP LNs. Left panels: Ki67⁺ LECs (arrow). Right panels: Ki67⁺ FRCs (blue represents Ki67; red, LyveI; and green, EYFP). Scale bar represents 10 μm. (E) Percentage of Ki67⁺ transgene-expressing cells in naive and reconstructed LNs. Evaluation of 10 high power fields per LN (mean ± SEM; n = 4 LNs). *P < .05.