FIGURE 2.

The chromaffin cells of the Zuckerkandl organ are grossly Schwann-cell-precursor-derived, as well as a small portion of the posterior trunk sympathetic ganglia. (A) Side view of whole-mount immunofluorescence against Plp1^YFP, TH and CART on an E12.5 embryo which received a single tamoxifen (TAM) injection at E11.5, showing the sympathoadrenal (SA) primordium area. Note the big accumulation of Plp1^YFP+ cells ventrally to the first TH⁺ cells and the lack of Plp1^YFP+ cells at the more overlying CART⁺ chain corresponding to the sympathoblasts of the sympathetic chain. (B,C,E) Immunofluorescence on cryosections against Plp1^YFP, CART and TH on an E15.5 embryo injected with TAM at E11.5 and analyzed at E15.5. Note the Plp1^YFP+/TH⁺ cells in the Zuckerkandl organ (ZO), sympathetic para-aortic ganglion (PAG, shown by white arrowheads) and adrenal medulla (AM). (D) Upper panel: immunofluorescence against Plp1^YFP, SOX10 and CART on peripheral nerves of E15.5 Plp1^YFP+ embryos injected with TAM at E11.5. Lower: quantification of recombination efficiency in SOX10⁺ cells of peripheral nerves (corresponding to total peripheral glial cells) of embryos TAM-injected on E11.5 and analyzed at E15.5 (69.63 ± 8.69%, N = 4). Filled arrowheads show Plp1^YFP+/SOX10⁺ glial cells and empty arrowheads show Plp1^YFP-/SOX10⁺ glial cells. (F) Quantification of recombination in chromaffin and sympathetic population in embryos TAM-injected on E11.5 and analyzed at E15.5 (for the ZO 44.77 ± 6.44%, anterior PAG 4.84 ± 1.38%, posterior PAG 11 ± 2.80%, AM 37.69 ± 5.46%, in all cases N = 4). Data are presented as mean ± SEM. Note the high percentage of Plp1^YFP+/TH⁺ cells in the chromaffin organs ZO and AM and the difference in percentage of Plp1^YFP+/TH⁺ cells between the posterior and anterior PAG. Scale bar in (A) = 100 μm, in (B–E) = 50 μm. SA primordium, sympathoadrenal primordium; ZO, Zuckerkandl organ; PAG (ant), para-aortic ganglion (anterior); PAG (post), para-aortic ganglion (posterior); AM, adrenal medulla.