Fig. 3

Expression of vax at early developmental stages in embryos of the onychophoran E. rowelli. Anterior is left in a, c, e and up in b, d, f; developing limbs are numbered. Arrowheads point to the ventromedial expression in the cephalic lobes. a Stage II embryo in ventral view. b Head of the same embryo as in A in ventral view. c Stage III embryo in ventral view. d Head of the same embryo as in C in ventral view. Dashed line indicates the posterior border of the cephalic lobes. e Stage IV embryo in ventral view. f Head of the same embryo as in E in ventral view. Abbreviations: at, developing antenna; cl, cephalic lobe; de, dorsal extra-embryonic tissue; jw, developing jaw; po, proctodeum; sp, developing slime papilla; st, stomodeum; ve, ventral extra-embryonic tissue. Scale bars: a, c, e: 200 μm; b, d, f: 200 μm