NRNAi induces high levels of ROS in blood cells, but not in the niche. ROS staining of freshly dissected lymph glands of control (Antp > mCD8-GFP, A–A′′), experimental (Antp > mCD8-GFP, NRNAi) (B–B′′), and (Antp > mCD8-GFP, NICD) (C–C′′) animals. High ROS is detected in the medulla and cortex of Antp > mCD8-GFP, NRNAi lymph glands. ROS levels are low or undetectable in the niche of all three genotypes (A′′, B′′, and C′′).