Adult mLNSC fate is locally determined. (A) FC^Confetti fate-mapping approach. (B) Fluorescent proteins mapping FAP expression from e15.5. (C) Probability distributions of a randomized Poisson distribution of fluorescent reporters (top), or the actual data (bottom). (D) MI was calculated for each iLN and compared with the MI derived from the randomized distributions. Data shown are 15 iLNs combined from two experiments. Statistical significance was determined using a paired t test: ****, P < 0.0001. (E and F) The relationships of fate-mapped MRCs and FDCs in single follicles was determined in FC^Confetti (+dox e15.5) mice. CD35⁺ FDCs (E) and RANKL⁺ MRCs (F), represented as a z-stack encompassing 20 µm. Arrows indicate linked cRFP⁺ cells; arrowheads indicate linked cYFP⁺ cells. See Videos 1 and 2 (E) and Videos 3 and 4 (F). White boxes indicate enlarged areas. Scale bars, 500 µm (B) or 100 µm (E and F). Data represent 15 iLNs from two experiments.