Controversies Surrounding Segments and Parasegments in Onychophora: Insights from the Expression Patterns of Four “Segment Polarity Genes” in the Peripatopsid Euperipatoides rowelli
Figure 10
Expression of hedgehog in embryos of E. rowelli.
Leg-bearing segments and corresponding limbs are numbered. Arrowheads indicate segmentally repeated stripes in the posterior portion of each developing limb. (A) Stage I embryo. Inset in the upper right corner shows a fluorescent micrograph (DNA labelling) of the blastoporal area from the same embryo. Arrows point to the position of the blastopore, which is surrounded by hedgehog expressing cells. (B) Posterior end of a stage IV embryo. Arrow indicates the expression around the proctodaeum. (C) Stage III embryo in lateral view showing repeated stripes of expression along the body. Arrowheads point to the emerging hedgehog domains in the posterior portion of each developing limb in the posterior half of the embryo. Note an elongated domain at the posterior border of the cephalic lobes (double-arrowhead). (D) Anterior end of a stage IV embryo in ventral view. Double-arrowhead points to the elongated domain at the posterior border of the cephalic lobes. Dotted line indicates the border between the ectoderm and the ventral extra-embryonic tissue. (E) Dorsal view of the same embryo as in D. Arrows point to the expression in the mesoderm at the bases of the developing antennae. Abbreviations: at, developing antenna; de, dorsal extra-embryonic tissue; jw, embryonic jaw; po, proctodaeum; sp, embryonic slime papilla; ve, ventral extra-embryonic tissue. Scale bars: 500 µm (A), 100 µm (B), 250 µm (C), 200 µm (D, E).