Fig. 2

meis1 and meis3 expression in Neoceratodus lobed fins. Whole-mount in situ hybridization in a, c, e–l pectoral and b, d pelvic lobed fins. a, b White arrowheads indicate meis1 transcript under the AER in a pectoral and b pelvic fin buds. c–g, i–k meis3 expression in the whole bud of c pectoral and d pelvic fins. b, d The white dashed lines highlight the margin of paired pelvic fin buds. a–d Square brackets indicate the AER. The black dashed lines indicate the stylopod-zeugopod boundary at chondrogenesis stages. e–g, i–k From st. 46 to st. 50, e, i meis1 and meis3 transcripts are first localized in the proximal cells of the pectoral lobed fin, f, j after they extend gradually in a PD striped pattern around cartilage condensations, g, k and then they show intersegmental expression (asterisks). h, l Double Alcian Blue/WISH labelings show proximal expression across the humerus region and the first transversal stripe near radius/ulna cartilages. Abbreviations: AER, apical ectodermal ridge; c, cartilage; h, humerus; m, mesenchyme; r, radius; u, ulna. Anterior to left; distal to top. Scale bars are 100 µm (a–d), 80 µm (e, f, i) and 50 µm (g, h, j–l)