Fig. 3

Lineage tracing reveals the expansion of juvenile FGFR3⁺ cells into the inner region of caudal NP. (a) FGFR3;mTmG mice were administrated with Tam at 2w and sacrificed at the different ages after chasing. Representative images show the dynamic changes of FGFR3⁺ lineage cells in caudal NP. FGFR3;mTmG mice received corn oil treatment at 2w and sacrificed at 7 m following is regarded as control (No Tam). The outer and inner region of NP is shown by the dotted boundary and inner circle of NP. Scale bars, 100 µm. (b) Percentages of FGFR3⁺ cells in both outer and inner region of NP increase continuously after tracing. **P < 0.01, ***P < 0.001, ****P < 0.0001, One-way ANOVA with post hoc Tukey test. (c) Mice were injected with EdU at 1w and sacrificed after chasing. Images at different chasing time show the positional variations of EdU⁺ cells in caudal NP. The outer and inner region of NP is shown by the dotted boundary and inner circle of NP. Scale bars, 100 µm. (d) Quantification of EdU⁺ NP cells in each region at different time in the EdU pulse and chase assay reveals decrease of EdU⁺ NP cells in outer region and increase of that in inner region. (e) Experimental design of the simultaneous tracing of FGFR3⁺ and EdU⁺ cells. R3;mTmG mice were administrated with EdU at 1w before receiving Tam at 2w and sacrificed at 2 m and 7 m. (f) Representative images of caudal NP imaged at 2 m and 7 m show that both the location shift of EdU⁺ cells and the expansion of FGFR3⁺ cells happen from outer region (annotated as OR) to inner region (annotated as IR) during chasing time. White box areas in the upper images (scale bars, 100 µm) are shown in higher magnification in the below (scale bars, 20 µm). Arrowheads indicate the colocalization of EdU^·+ NP cells with FGFR3-lineaging cells