Fig. 5

Expression of H⁺-V-ATPase subunits in early chick embryos. (A-D) Whole-mount in situ hybridization for H⁺-V-ATPase subunits; green arrows indicate normal location of staining. (A) Whole-mount in situ hybridization for subunit A in stage two chick embryos. Staining is in the primitive streak. (B) Whole-mount in situ hybridization for subunit A at stage 3 showing staining along the length and through to the tip of the primitive streak. (C) Section through the primitive streak of a stage 3 embryo reveals expression in the mesoderm. (D) Stage 4^- embryo probed for subunit F, which, like subunits A and B, is found in the primitive streak, extending through Hensen's node. (E-H) Immunostaining for H⁺-V-ATPase subunits. (E) Stage 2⁺ chick embryo reveals subunit B along the length of the primitive streak. (F) In stage 3 chicks, staining for subunit B is in the streak and the node. (G) Cross-section through the streak of a stage 3 embryo showing subunit a staining in the mesoderm (M); Ec, ectoderm; En, endoderm. (H) Subunit B staining in a stage 4 chick. The streak and node are both positive.