Fig. 8. Stage 18 in Development and gastrulation in Hyloxalus vertebralis and Dendrobates auratus (Anura: Dendrobatidae)

Fig. 8. Stage 18: Muscular activity stage of H. vertebralis and D. auratus embryos. Micrographs of H. vertebralis embryos are shown in A, C, E, and micrographs of D. auratus embryos are shown in B, D, F. Sections shown in C–D were stained for cell nuclei. (A) Lateral view of an embryo. (B) Dorsal view of an embryo. The gill buds were visible on each side of the head in embryos of both species. (C–D) Cross sections through the trunk. The cavity in D corresponds to the gut. (E–F) Horizontal sections. A row of numerous somites was detected on each side of the notochord. The brain and the otocysts were visible in E, and the gut was visible in F. bn, brain; ec, ectoderm; g, gut; gb, gill bud; hy, hyoid arch; ma, mandibular arch; n notochord; nt, neural tube; ot, otocyst; p, pronephros; s, somite.