Fig. 10

Expression of Msx at consecutive developmental stages in embryos of the onychophoran E. rowelli. Anterior is left in E, F, and up in G, H; developing legs are numbered. A Cross section of a stage III embryo showing the expression in the ventrolateral ectoderm (arrowhead) and developing nerve cord (arrow). B Same cross section as in A stained with DAPI. Developing nerve cord is indicated with dashed lines. C Cross section of a stage IV embryo showing the expression in the ventral ectoderm (arrowhead) and developing nerve cord (arrow). D Same cross section as in C stained with DAPI. Developing nerve cord is indicated with dashed lines, developing neuropil is indicated with asterisks in A and B. E Late stage V embryo in ventrolateral view. Note the strong expression in the distal portion of the developing antennae (inset). F Stage VI embryo in ventrolateral view. Note that the signal is stronger in the slime papilla segment (asterisks) than in the subsequent segments. Note also the decreased expression in the developing antennae (inset) as compared to the embryo in E. G Head of late stage V embryo in dorsal view. H Head of a stage VI embryo in dorsal view. Arrows in G and H point to uncharacterized anterior brain neuropils; arrowheads indicate the putative olfactory lobes. Abbreviations: an, antennal tracts; at, developing antenna; cn, central brain neuropil; cp, connecting piece (cf. Ref. [141]; “medullary connective” sensu Whitington PM and Mayer G [111]); cx, brain cortex; de, dorsal extra-embryonic tissue; jw, developing jaw; mo, mouth; po, proctodeum; sp, developing slime papilla; ve, ventral extra-embryonic tissue. Scale bars: A–D: 50 µm; E, F: 500 µm; G, H: 200 µm