Figure 10. The caudal tip of the CLE shows paraxial mesoderm but not neural potency.

(A) Representative examples of L/St5 heterotopic grafts (numbers in brackets identify individual embryos depicted in (B–C). (Aa, Af and Ak) Cells immediately after grafting. Arrowheads show grafted cell position. (Ab, Ag and Al) Whole embryo after 48 hr ex vivo culture. (Ac–e, Ah–i and Am–o) Rostral to caudal transverse sections. (Aa–e) L/St5 AGFP7 to St1-3 grafts shows LVM-fated cells can switch fate to form PXM. (Af–j) L/St5 βcatCKO:sGFP to St1-3 grafts show a similar contribution pattern to control grafts. Non-integrated clumps near the notochord were observed in 3/7 embryos (see Figure 9—figure supplement 2H). (Ak–o) L/St5 to Br grafts show robust contribution to the paraxial mesoderm. (B–C) Grafting of L/St5 donor cells to the primitive streak (B) or to Br (C). Graph format is the same as in Figure 6. (D–E) Quantitative analysis of L/St5 graft contribution. Left, the percentage of PXM vs LVM (in D) or NT (in E) contribution in all scorable sections. Right, the percentage of embryos with TBM (in D) or dorsal CNH (in E) contribution. (F) Ectopic over-expression of Sox2 in L/St5 cells (n = 6 embryos). (Fa) L/St5 cells of AGFP7 embryos were electroporated with CAG-Sox2-T2A-tdTomato plasmid before grafting to Br of WT hosts. (Fb–c) Electroporated cells immediately after grafting (Fb) and after 4 hr culture (Fc). (Fd–f) Grafted embryo after 48 hr in vitro growth. Arrowheads show areas containing not well-integrated cells (orange). Green cells were not electroporated at the start and contributed to the PXM and LVM as before. (Fg–h) Axis and TB sections show orange cells never contribute to the NT. (G) Summary of L1-3 and L/St5 heterotopic grafts. Coloured bars represent the contribution to different axial tissues. Contribution in the neural CNH and TBM is represented by a black square or a grey circle, respectively. N, neural; PXM, paraxial mesoderm; LVM, lateral/ventral mesoderm; non-N, non-neural clumps; TBM, tail bud mesoderm; N-CNH, dorsal (neural) part of the CNH.

DOI: http://dx.doi.org/10.7554/eLife.10042.023

Figure 10—figure supplement 1. Overall lateral/ventral and tail bud mesoderm contribution.

(A) Percentage of total embryos and sections containing GFP⁺ cells in the lateral/ventral mesoderm. LVM contribution is very rare in L1 grafts. Note that the L2–3 grafts produced LVM at different sections along the axis, whereas L/St5 derived LVM was always found posterior to the hindlimb. (B) TBM contribution in all L/St5 grafts is limited. (C) Two L/St5 to Br sections illustrate the limited NT contribution in embryo 7.03.

DOI: http://dx.doi.org/10.7554/eLife.10042.024

Figure 10—figure supplement 2. Somite contribution in heterotopic LPMP grafts.

(A) Different L/St5 grafts performed. (B) Representative sections taken from grafts in A. Green, grafted cells; cyan, autofluorescence channel; arrows, notochord position; nt, neural tube; pxm, paraxial mesoderm.

DOI: http://dx.doi.org/10.7554/eLife.10042.025