Fig. 9
Expression of Msx at consecutive developmental stages in embryos of the onychophoran E. rowelli. Anterior is left in A–C, E–K; developing legs are numbered. Insets in B and F show the respective embryos stained with DAPI. A Stage I embryo in lateral view. B Same embryo as in A in ventrolateral view, superimposed light micrograph and DAPI image. Arrowheads point to the transverse furrows. C Detail of a stage I embryo in ventral view. Arrowheads point to transverse furrows. D Cross section of the first leg-bearing segment, dorsal is left. Arrowhead points to the expression in the mesoderm. E Detail of a stage I embryo in lateral view. Superimposed light micrograph and DAPI image. Transverse furrows are indicated by dashed lines. F Stage III embryo in lateral view. G Detail of the same embryo as in F in ventrolateral view. Anterior and posterior domains in the ventral ectodermal thickenings are marked by empty and filled arrowheads, respectively. H Posterior end of stage III embryo in lateral view. I Stage IV embryo in lateral view. J Detail of the same embryo as in I in ventral view. Arrowheads point to mesodermal domains in the limb buds. K Stage IV embryo in ventrolateral view. Anterior and posterior domains in the ventral ectodermal thickenings are marked with empty and filled arrowheads, respectively. Abbreviations: at, developing antenna; cl, cephalic lobe; de, dorsal extra-embryonic tissue; js, jaw segment; jw, developing jaw; po, proctodeum; sp, developing slime papilla; ss, slime papilla segment; ve, ventral extra-embryonic tissue. Scale bars: A–C, G, H, J, K: 200 µm; F, I: 500 µm; D, E: 100 µm