Figure 3
From: Mesodermal origin of median fin mesenchyme and tail muscle in amphibian larvae
Results of fate mapping experiments of neural fold in the axolotl neurula (stage 15).
Only posterior trunk neural fold regions contribute to posterior trunk/tail muscle and fin mesenchyme. A-C, homotopic transplantation of three defined GFP+ neural fold regions (accentuated in green) from a GFP+ donor (stage 15) to a white (d/d) host (stage 15) and visualization of graft-derived GFP+ cells in larvae at stage 41 (1 cm length). White arrowheads indicates position of cloaca in larvae. A’–C’ and A”, transverse cryosections through larvae shown in A–C containing GFP+ grafts; dashed lines in A–C indicate sectioning planes; sections are overlays of fluorescence images. Dapi, blue; anti-12/101 (muscle), red; anti-GFP, green. A, A’ and A”, GFP+ region3 fold gives rise to few muscle cells in tail myotomes, to few mesenchymal cells in the dorsal and ventral tailfin and to some tail epidermis (upper and lower seam of tailfin). B and B’, GFP+ region2 fold contributes cells to the spinal cord, dorsal root ganglia and fin epidermis in the mid trunk. The labelling of the epidermis is not visible here in B‘ but optimal further posteriorly to the ganglia (see Fig. S1). C and C’, GFP+ region1 gives rise to cells in the spinal cord, dorsal root ganglia, fin epidermis and to the middle lateral line nerve in the anterior trunk. D–F, higher enlargements of boxed area in A’. Presence of GFP+ mesenchymal cells in the dorsal tailfin after grafting GFP+ fold region3. Number of experiments: A, 30; B, 5; C, 5. Abbreviations: df, dorsal tail fin; vf: ventral fin; mes: mesenchymal cell; my, myotome; epi, epidermis; spc, spinal cord; lln, lateral line nerve; drg, dorsal root ganglia; spn, spinal nerve; not, notochord. Scale bars, 1 mm (A–C), 200 μm (A’), 20 μm (F) and 100 μm (A”, B’, C’).
